No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Soil organic carbon sequestration in agroforestry systems. A review
Abstract
The increase in atmospheric carbon dioxide (CO2) concentrations due to emissions from fossil fuel combustion is contributing to recent climate change which is among the major challenges facing the world. Agroforestry systems can contribute to slowing down those increases and, thus, contribute to climate change mitigation. Agroforestry refers to the production of crop, livestock, and tree biomass on the same area of land. The soil organic carbon (SOC) pool, in particular, is the only terrestrial pool storing some carbon (C) for millennia which can be deliberately enhanced by agroforestry practices. Up to 2.2 Pg C (1 Pg = 10(15) g) may be sequestered above- and belowground over 50 years in agroforestry systems, but estimations on global land area occupied by agroforestry systems are particularly uncertain. Global areas under tree intercropping, multistrata systems, protective systems, silvopasture, and tree woodlots are estimated at 700, 100, 300, 450, and 50 Mha, respectively. The SOC storage in agroforestry systems is also uncertain and may amount up to 300 Mg C ha(-1) to 1 m depth. Here, we review and synthesize the current knowledge about SOC sequestration processes and their management in agroforestry systems. The main points are that (1) useful C sequestration in agroforestry systems for climate change mitigation must slow or even reverse the increase in atmospheric concentration of CO2 by storing some SOC for millennia, (2) soil disturbance must be minimized and tree species with a high root biomass-to-aboveground biomass ratio and/or nitrogen-fixing trees planted when SOC sequestration is among the objectives for establishing the agroforestry system, (3) sequestration rates and the processes contributing to the stabilization of SOC in agroforestry soils need additional data and research, (4) retrospective studies are often missing for rigorous determination of SOC and accurate evaluation of effects of different agroforestry practices on SOC sequestration in soil profiles, and (5) the long-term SOC storage is finite as it depends on the availability of binding sites, i.e., the soil's mineral composition and depth. Based on this improved knowledge, site-specific SOC sequestering agroforestry practices can then be developed.
... Agroforestry systems provide options to mitigate climate change with the possibility to increase crop yields, increase agricultural productivity, improve soil fertility, control erosion, conserve biodiversity (Feliciano et al., 2018). Agroforestry systems have received increased attention because of their capacity to sequester carbon dioxide from the atmosphere in above and belowground biomass and in the soil (Lorenz and Lal, 2014). In Brazilian semiarid regions the agroforestry systems enhanced soil quality (Maia et al., 2006), decreased the incidence of fires and increased population incomes and life quality (Araújo Filho, 2013). ...
... The impacts of agricultural management practices on soil quality can take decades to be identified (Bai et al., 2018), but long-term monitoring approaches associated with scenario projections can help to anticipate these impacts. Simulation models become a feasible alternative to study the temporal SOC dynamics in complex agroecosystems (Lorenz and Lal, 2014). Worldwide, the Century model is one of the most used (Parton et al., 1987) and the model was initially developed to simulate the SOC dynamics under natural pastures (Parton et al., 1987), but later was adapted to study SOC in forest and different agricultural managements. ...
... Agroforestry systems (AFs) have been used in several regions around the world and are characterized by sustainable land use, for their contribution to C sequestration (Lorenz and Lal, 2014) and mitigation of climate change (Nair et al., 2009). The simulated scenarios show the importance of the management and evaluation of agroforestry systems in the Caatinga biome over 100 years. ...
Understanding the effects of agroforestry systems (AFs) on soil organic carbon (SOC) requires long-term experiments , but scenarios simulations can anticipate the potential of these systems to sequester or lose carbon (C). This study aimed to simulate the SOC dynamics in slash and burn management (BURN) and AFs using the Century model. Data from a long-term experiment implemented in the Brazilian semiarid region were used to simulate SOC dynamics under BURN and AFs situations, and the natural vegetation (NV) "Caatinga" as a reference. BURN scenarios considered different fallow periods (0, 7, 15, 30, 50 and 100 years) among cultivation of the same area. The two types of AFs (agrosilvopastoral-AGP and silvopastoral-SILV) were simulated in two contrasting conditions: (i) each one of the AFs and also NV area were permanently conducted with no rotation among these areas; and (ii) the two AFs and NV rotated among them every 7 years. The correlation coefficients (r), coefficients of determination (CD) and coefficients of residual mass (CRM) showed adequate performance, meaning that the Century model is able to reproduce the SOC stocks in the slash and burn management and AFs situations. The equilibrium points of NV SOC stocks stabilized around 30.3 Mg ha − 1 , as similar to the measured average of 28.4 Mg ha − 1 at field conditions. The adoption of BURN without a fallow period (0 years) resulted in a reduction of 50% of SOC, approximately 20 Mg ha − 1 , after the first 10 years. Permanent (p) and rotating (r) AFs management systems recovered (in 10 years) fast to the original SOC stocks, resulting in higher SOC stocks than NV SOC at equilibrium. The fallow period of 50 years is necessary to recovery SOC stocks in the Caatinga biome. The simulation shows that the AFs systems increase more SOC stocks than observed in natural vegetation in long-term.
... Integrating NFS in AFSs not only improves soil N status, but also enhances the AFS's potential to sequester C and improve soil health and quality (Nair et al., 2009a;Kaonga, 2005;Lorenz and Lal, 2014;Sebukyu and Mosango, 2012;Dubiez et al., 2019). Enhanced SOC sequestration in NFS-based agroforestry may be attributed to the decomposition of large quantities of high-quality organic matter from N 2 -fixing trees (von Haden et al., 2019). ...
... Cardinael et al. (2018a) also highlighted the difficulty of correctly estimating changes in SOC stocks in AFSs due to the lack of rigorous long-term measurements, as already reported by Nair et al. (2009a) and Nair (2012). Even when SOC is measured in AFSs, it is rarely compared to an adequate reference system (Lorenz and Lal, 2014;Cardinael et al., 2018a;Feliciano et al., 2018). ...
... Cardinael et al. (2018a),Chatterjee et al. (2018),Feliciano et al. (2018),Lorenz and Lal (2014),Nair et al. (2009a),Shi et al. (2018) (ii) Socioeconomic barriers Social and political contexts Policymakers (lack of policies) Governments (insufficient support of infrastructure, etc.) Lack of training or extension services Lack of funds, infrastructure or AFS-enabling projects in the regions with the greatest potential to sequester C Land tenure issuesNair et al. (2009a), Mbow et al. (2014), Stainback et al. (2012), Bucagu et al. (2013), Foundjem-Tita et al. (2013) ...
Agroforestry is a land-use system where woody perennials are deliberately combined with agricultural crops and/or livestock on the same land-management units in some form of spatial arrangement or temporal sequence. Agroforestry has the potential to respond to multiple challenges related to soil carbon sequestration including soil fertility improvement, land restoration, food security and adaptation and resilience to climate change. In this chapter, we show how agroforestry systems (AFSs) address several of the above-mentioned challenges, and play a key role in boosting soil carbon sequestration (SCS) and improving soil functions. Other co-benefits are also considered, i.e., soil and ecosystem services, and the wellbeing of rural populations (increase in income, access to non-timber products, etc.), mainly in the less developed countries. Attention is also paid to the main barriers, which may lessen or halt SCS in AFSs. We make recommendations for implementing and improving AFSs to foster SCS and to meet the challenges faced by human societies in the 21st century.
... The results also suggest that the impact of the length of cultivation and fallow periods on soil-C is also dependent on the presence or absence of the arboreal component. The finding that SOC concentrations and stocks remained unchanged following DM conversion to tree-based SC and following SC conversion to woody fallow is in line with similar studies over the world (Bruun et al., 2021;Magalhães and Mamugy, 2020;McNicol et al., 2015) and also consistent with the studies analysing woodland conversion to agroforestry systems (Kassa et al., 2017;Lorenz and Lal, 2014). Recall that tree-based SC is an agroforestry system, as it integrates trees into agricultural areas (Brookfield and Padoch, 1994;Raintree and Warner, 1986;Thrupp et al., 1997). ...
... Apart from the abovementioned factors that enhance soil C storage in tree-based SC compared to treeless SC, there are other reasons to consider. The roots of the trees have the potential to recover nutrients from below the crop rooting zone, promoting SOC sequestration (Lorenz and Lal, 2014). Mixed trees and higher species diversity observed in tree-based SC compared to treeless SC result in increased fine root productivity (Meinen et al., 2009;Schroth, 1998), increasing thus SOC storage, as most soil-C is derived from roots rather than shoots and leaf litter (Kell, 2012;Rasse et al., 2005). ...
... The reasons raised here regarding the superiority of tree-based SC over treeless SC are valid when comparing WF to GF, and tree-based SC to GF with regard to soil C sequestration and storage, as tree-based LULCs are superior to any treeless LULCs (Lorenz and Lal, 2014). ...
The main driver of deforestation and degradation of miombo woodland is shifting cultivation (SC). SC is the main farm system and livelihood of the people in miombo woodlands. Assessing the current body of knowledge, the following apparent gaps were identified: (i) researches analysing the response of soil-C to woodland (miombo) conversion to SC are contradictory; (ii) studies reporting all the stages of agriculture-induced ecological succession (woodland, shifting cultivation, fallow vegetation, and reconversion to shifting cultivation or to woodland) are lacking. The response of soil-C to (1) dry miombo woodland (DM) conversion to SC, (2) SC conversion to fallow vegetation, (3) reconversion of fallow vegetation to SC, (4) the length of the cropping and fallowing periods, and (5) land-use intensification, was studied. The study was carried out in a landscape mosaic consisting of treeless SC, tree-based SC, grass fallow (treeless SC-fallow), and woody fallow (tree-based SC-fallow). DM conversion to treeless SC resulted in depleted soil-C by up to 72%; the depletion increased with the increasing length of the cultivation period. The fallow period (grass fallow) recovered part of the soil-C lost during the cultivation period: grass fallow lands were approximately three-fold larger in soil-C stocks than treeless SC lands. Soil-C increased with increasing grass fallow age. No significant changes in soil-C were observed when DM was converted to tree-based SC, or when tree-based SC lands were left under fallow (woody fallow); consequently, soil-C did not vary with the increasing lengths of cultivation and fallow periods. Woody fallows were up to 45% higher in soil-C stocks than grass fallows. Reconversion of grass fallow to treeless SC resulted in soil-C loss; no changes were observed when woody fallows were reconverted to tree-based SC. Land-use intensification by increasing the frequency of SC cycles did not alter soil-C in either treeless or tree-based SC. It was concluded that, under the study area conditions, the response of soil-C to agriculture-induced land-use changes depends mainly on the presence or absence of the arboreal component. Maintaining or introducing the arboreal component is recommended to avoid or mitigate soil-C loss following DM conversion to SC.
... In this analysis, only two management options affecting SOC, tillage treatment and residue management, are considered. High SOC sequestration potentials on cropland are argued to be only achieved by applying a variety of management options, e.g., additional restoration of degraded land (Griscom et al., 2017;Lal, 2003b), agroforestry (Lorenz and Lal, 2014;Torres et al., 2010), biochar (Smith, 2016), biowaste compost (Mekki et al., 2019), which add forms of organic material which increase turnover times of SOC. A combination of these different practices is more likely to achieve higher SOC sequestration rates on cropland . ...
... These include the application of manure, which can increase SOC by 0.1 ± 0.05 Mg C ha -1 yr -1 (Buysse et al., 2013), the management of cover crops (Corsi et al., 2012), which was reported to be able to increase SOC by 0.32 Mg C ha -1 yr -1 (Poeplau and Don, 2015) and 0.54 ± 0.57 Mg C ha -1 yr -1 (reported as 1.97 ± 2.1 Mg CO2-eq. ha -1 yr -1 in Abdalla et al. (2019)), and agroforestry (Cooper et al., 1996;Ramachandran Nair et al., 2009), which may sequester up to 2.2 Pg C globally after 50 years of agroforestry implementation (Lorenz and Lal, 2014). Majumder et al. (2008) reported a minimum return rate to the soil of 3.56 Mg C ha -1 yr -1 to maintain SOC levels and to compensate for SOC losses from cropping practices, which none of the management options mentioned above can achieve alone. ...
Klimawandel und Bodendegradation üben Druck auf die Nahrungsmittelproduktion sowie auf die Fähigkeit des Bodens zur Minderung des Klimawandels beizutragen aus. Bodendegradation hat negative Auswirkungen auf die Bodenqualität. Ziel dieser Arbeit ist die Analyse der Effekte von landwirtschaftlich getriebener Bodendegradation, vor allem durch Pflügen und dem Umgang mit Ernterückständen. Es wird ein Überblick über das Thema Bodendegradation gegeben, gefolgt von Erweiterung des globalen Ökosystemmodells Lund-Potsdam-Jena-managed-Land (LPJmL) um eine detaillierte Prozessabbildung von Pflugpraktiken und Effekten von Ernterückständen. Diese ermöglicht die Analyse der Effekten von landwirtschaftlichen Managements auf die Anpassung und Minderung des Klimawandel. Das Modell kann die Effekte von naturerhaltender landwirtschaftlicher Bewirtschaftung (im Englischen bekannt als Conservation Agriculture) auf Kohlenstoffvorräte im Boden und CO2 Emissionen simulieren. Im letzten Teil wird die historische Dynamik der Entwicklung von Bodenkohlenstoff (engl.: Soil Organic Carbon – SOC) und die Effekte von Annahmen zum zukünftigen Management unter unterschiedlichen Klimaszenarien gezeigt. Die Ergebnisse zeigen, dass durch die historische Umwandlung von natürlicher Vegetation zu landwirtschaftlicher Fläche bis zu 215 Pg SOC im Boden verloren gegangen sind. Bis zum Ende des Jahrhunderts könnten weitere 38 Pg SOC zusätzlich verloren gehen, wird die heutige landwirtschaftliche Fläche nicht nachhaltig bewirtschaften. Die Bewirtschaftung mit dem Pflug zeigt einen geringen Einfluss auf die Kohlenstoffvorräte des Bodens, während die Wahl der Behandlung von Ernterückständen erheblich Einfluss hat. Die Rückführung von Ernterückständen hat positive Einflüsse auf Bodenwassergehalt und Ernteproduktivität, mit regionalen Unterschieden. Insgesamt zeigen 46% der heute Landwirtschaftsfläche das Potenzial zur Steigerung des Bodenkohlenstoff, während mindestens 52% Kohlenstoff im Boden verlieren könnten.
... A estimativa do potencial em escala global desses sistemas em sequestrar carbono é de 1,1 Pg a 2,2 Pg de C (1 Pg = 1.015 g ou 1 bilhão de toneladas) durante 50 anos, na parte aérea e no solo. Entretanto, esse potencial varia de acordo com o modelo, composição das espécies, idade das espécies componentes, localização geográfica, fatores ambientais e práticas de manejo (Lorenz;Lal, 2014). ...
... A estimativa do potencial em escala global desses sistemas em sequestrar carbono é de 1,1 Pg a 2,2 Pg de C (1 Pg = 1.015 g ou 1 bilhão de toneladas) durante 50 anos, na parte aérea e no solo. Entretanto, esse potencial varia de acordo com o modelo, composição das espécies, idade das espécies componentes, localização geográfica, fatores ambientais e práticas de manejo (Lorenz;Lal, 2014). ...
... On a global scale, AFS may on average store up to 300 MgC ha -1 to 1m depth. Extrapolated over a time span of 50 years, this would imply an overall sequestration of 2.2 PgC considering all AFS worldwide, although the global extent of AFS is considered as highly uncertain (Lorenz and Lal, 2014) . Considering that fossil fuel use and land use change have emitted 555 ± 55 PgC by 2015 (Mengis et al., 2018) , this may play a small but crucial role in reducing anthropogenic C emissions. ...
... Considering that fossil fuel use and land use change have emitted 555 ± 55 PgC by 2015 (Mengis et al., 2018) , this may play a small but crucial role in reducing anthropogenic C emissions. Important factors that may affect the potential of C sequestration in AFS are the employment of a reduced soil disturbance regime, the selection of species with a high root-biomass-to-abovegroundbiomass ratio as well as the presence of N-fixing trees (Lorenz & Lal, 2014). Although it should be noted that Tree rows, which usually only make up a small proportion of the surface area in AFS, contribute up to 50% of the additional carbon stocks in AFS (Cardinael et al., 2017) . ...
Agroforestry systems (AFS) show large potential to tackle global problems on various fronts, for example by reducing biodiversity loss, whilst also increasing sequestration of carbon as well as efficiency of N-cycling. To cope with the growing demand for AFS in Austria, the need arises to establish agroforestry research stations (AFRS). This study thus proposes preliminary recommendations for an AFRS design at the experimental station Groß Enzersdorf (VWG) using a systemic approach thereby accounting for AFS design often being multi-faceted. This is done through the novel approach of applying the tree scoring method, common in tropical agroforestry, in a temperate context. This may help to objectify tree selection for AFS, which to this date is rarely ensured. The experimental design of three AFRS case studies is further reviewed in order to analyse their applicability to an AFRS at the VWG. With a strong focus on the methodology of the tree ranking method, this study highlights the methods potential for improvement by pointing out major research limitations, such as the strong reliance on extensive tree attribute data, which is currently not available. Rather than considering all potential tree species, only a selection of twelve species was evaluated using the scoring method, thus the results should be regarded as preliminary. This study proposes the use of species that performed well in the scoring method, to be integrated into on-farm field trials, thus testing already existing concepts of AFS in their potential to provide important functions, such as reducing wind erosion, which may be highly relevant in the Marchfeld region. Overall, this study highly recommends the establishment of an AFR at the VWG, which could play a leading role in sustainable food production in Austria.
Keywords:
Agroforestry, Agroforestry Design, Agroforestry Research, Tree Selection, Tree prioritization, Experimental station Groß-Enzersdorf
... Agroforestry is a promising land-use practice with which to promote C biosequestration (the biologically mediated uptake and conversion of CO2 into inert, long-lived, Ccontaining materials) and reduce GHG emissions from soil [14][15][16]26,[67][68][69][70]. In general, the structures, components, farming activities, and management practices of agroforestry systems are very diverse; furthermore, agroforestry systems are structurally and functionally more complex than either croplands, grasslands, or tree monocultures [30,70]. ...
... Although consensus does not always exist, most studies show that planting trees in agricultural (especially arable) environments leads to an increase in soil organic C stocks [71,[75][76][77][78]. However, a limited number of field experiments have been specifically conducted to test the effects of agroforestry practices on soil organic C, and quantitative information about belowground C inputs in agroforestry systems is thus missing [68]. However, if it is assumed that average C sequestration in the selected agricultural land suitable for agroforestry in Latvia is 2.75 t C ha −1 yr −1 , and according to the Aertsens et al. (2013) [14], the total amount of potentially sequestered C is 966.6 kt C yr −1 or 3544.2 kt CO2 yr −1 (including 843.2 kt C yr −1 in areas without underground drainage systems). ...
The role of trees on agricultural land is predicted to increase rapidly in order to achieve biodiversity, environmental, and climate goals. This study demonstrated the selection and evaluation approach and assessed the suitable agricultural land for agroforestry practices in hemiboreal Latvia, which was selected as the demonstration area by synthesizing knowledge of environmental sciences, remote sensing, and relevant legislation on land use and management. The total area of agricultural land suitable for agroforestry was estimated to be 14.1% of the total agricultural land in Latvia (351.5 kha). The selected agricultural land mainly comprised semihydromorphic soils; the dominant soil texture was loamy sand. Current dominant land use in the selected agricultural land consisted of heterogeneous agriculture and pastures; however, the selected agricultural parcels were outside intensive agricultural production for the most part—only 0.38% of the total selected agricultural land was accepted to receive state support and/or EU support to farmers under the Common Agricultural Policy (CAP). Considering the lengthy process of implementation of new agricultural-land-management practices, as well as taking into account the ambitious timeframe for reaching biodiversity, environmental, and climate goals, we recommend reducing hindrances to the introduction of agroforestry systems. The provided selection and evaluation approach is transferable to other countries and regions by adaptation of the elaborated methodologies to available country-specific spatial information and data
... Agroforestry systems are frequently highly yielding, sequestering a considerable quantity of Greenhouse Gases (GHG) from the air and stock the carbon (C) in standing tree (biomass), soil organic manure, and collected products of biomass [41]. A.F.S. carbon storage capacity is undetermined, although it is estimated to sequester up to 300 Mg C ha -1 in 1 m deep soil [42]. In their studies, [43,44] showed that agroforestry has higher carbon concentrations than pastures or field crops. ...
... In alley cropping systems, the distance within the tree rows is generally sheltered by native or sowed herbaceous plants; moreover, soil in between tree rows is generally not tilled, favouring organic carbon stocking [59]. Additionally, straight carbon inputs to the soil can be likely augmented by a few agroforestry uses; these comprise (a) restoring to the soil as mulch pruning of woody species and permitting copious tree litter to decay on-site, (b) permitting livestock to graze and add manure to the soil, (c) during crop fallow periods, allowing woody species to grow and add surface, (d) incorporating trees and their litter input in animal production systems, (e) benefiting from soil carbon inputs of crops grown in the early steps of the implementation of forestry [42] The effect of air pollution from GHG emissions is estimated to have reduced Saudi Arabia population life expectancy by 1.5 year [60]. The Saudi Green Initiative (S.G.I.) aimed to raise vegetation cover, reduce carbon emissions, combat pollution and land degradation, and preserve marine life. ...
Aims: Most of the land area of Saudi Arabia is either arid or hyper-arid. In the past decades, many efforts have been exerted to increase the green cover in Saudi Arabia, the most recent of which is the Saudi Green Initiative (S.G.I.), launched in 2021. S.G.I.’s main objectives are to increase the green land surface area and decrease carbon emissions. In this paper, the role of dryland agroforestry in mitigating the effects of climate change was reviewed, and its contribution to fulfilling S.G.I. was discussed. Methodology: Previously published literature, scholarly research articles, and conference proceeding papers, on agroforestry systems (A.F.S), carbon sequestration and nutrient dynamics under A.F.S over the past 34 years were critically reviewed, examined, and analysed to find various applications of AFS for climate change mitigation and carbon sinks with focus on arid land. Results: Forests are a vital source for climate change mitigation and adaptation and play a vital role as carbon sinks. A.F.S, eco-friendly and environmentally viable land use and management, provide immense potential to sequester carbon (C). A.F.S. is a reliable tool for increasing C sequestration. As a result of the worth granted to non-timber products, the application of A.F.S. could likewise reduce C emissions to the air by reducing the odds of concrete cutting of trees. Moreover, tree components are a source of C for the soil by means of root and leave decomposition. Conclusion: In the perspective of the high threat facing humanity paused the climate variability and climate change, many nations and countries have taken various measures to tackle it which included protecting natural forests, afforestation, managed the natural regeneration of green cover. A.F.S leads to better land-use efficiency, increases the green cover, and thus helps in mitigating climate change.
... It also drives deforestation and land-use change and is one of the largest sources of carbon emissions in the global South ( Pendrill et al., 2019). Agroforestry and other trees on farms can support habitat connectivity and biodiversity conservation (Somarriba et al., 2017;Dawson et al., 2013), greenhouse gas sequestration (HLPE 2019), water management (Lorenz et al., 2014), and other ecosystem services. Trees on farms can also generate new income opportunities to farmers (Kassie 2018;FAO 2005FAO , 2019, improve food security (van Noordwijk 2019; Somarriba et al., 2017), and have cultural significance (Moreno et al., 2018;Torralba et al., 2016). ...
Native trees are central elements of sustainable agriculture, providing economic futures to rural populations while safeguarding biodiversity and ecosystem services. We present a diagnostic methodology for (i) identifying 'incentive opportunities' for farmers to plant and manage trees on farms; (ii) proposing targeted packages of incentive and finance instruments; and (iii) describing levers for policy integration to support their implementation. In two case studies from Uganda and Peru, the 'incentive opportunities' consist of providing technical and financial support to farmers for planting and managing trees, generating income sources from native trees and support from the beneficiaries of tree-based ecosystem services, and eliminating incentives for tree removal. Many instruments to promote trees on farms already exist, but implementation is hampered by weak and fragmented institutions, limited funding and low political priority. The proposed methodology can guide the development of incentive instruments as part of implementing policy strategies for integrated biodiversity conservation and sustainable development.
... However the fact that is unknown to layman is not all of the CO2 that is being released through the anthropogenic activities add up to the atmosphere, a significant part of it is being taken up by the land-based sinks (Lorenz & Lal 2014). For instance Peter et al. (2012) reported in the time period of 2002 to 2011 on an average about 28% of anthropogenic CO2 emissions were taken up by land-based sinks. ...
With the rising concern for global warming due to emission of green house gases, the need for mitigation of the hazard has gained momentum. Amid such time Carbon-sequestration has emerged as a promising solution. Among various systems or biomes which contribute to C-sequestration the age old practice of agro-forestry has been reported to be an excellent option in comparison to other systems of single species cropping and grazing systems. This article is aimed to throw light on what is agro-forestry and why it has gained importance in field of C-sequestration?
... In cases where there are limitations to the development of seral stages, natural regeneration can be optimized by planting nurse species, such as nitrogen xers or species that reduce luminosity and water loss (Montesinos-Navarro et al. 2017; Fagundes et al. 2018). Additionally, agroforestry systems have the ability to sequester and store carbon both above and below ground, which is comparatively higher than that stored by monoculture systems (Lorenz and Lal 2014) that are common in the Brazilian semi-arid region. When implemented in urban areas, agroforestry systems provide aesthetic improvements and important ecosystem services. ...
The Brazilian semi-arid region is characterized by scarce water and often saline soils, and the agricultural practices there contribute to desertification. Most of the land in this region is used for subsistence and income generation through the use of forestry resources, but the traditional management practices of clearing areas with fire and cutting trees result in long-term ecosystem degradation. Agroforestry systems (AS) are an alternative to traditional systems that incorporate ecological concepts and aim to increase ecosystem services while maintaining ecological relationships. This study aimed to analyze the implementation of an agroforestry system in a degraded urban area, estimate the costs of implementation, and observe the development of vegetation after 3 years. The initial attempt to implement the system failed due to direct seeding, but the method was changed after 6 months by using 4-month-old seedlings. The costs of the system involved preparation and planting expenses, as well as maintenance. All individuals in the sample area were measured for diameter, height above ground, and maximum height, and their phytosociological parameters were calculated. The study found that agroforestry systems are feasible in the semi-arid region and that species such as Ceiba, Gliricidia, and Moringa have fast growth and can increase organic matter in the semi-arid systems. After 3 years, the system had a basal area of 6.37 m²/ha and a carbon stock of 17.69 Mg/ha. The implementation costs were R$ 5,120.47 ($ 988.68), totaling R$ 57,468,79/ha ($ 11,096.29/ha), which were considered relatively low compared to other studies on degraded area restoration. ASs can be seen as an alternative for small producers, allowing them to generate income, ensure conservation, and improve social conditions, ensuring sustainability.
... Thinning and pruning of trees may reduce SOC sequestration by reducing litter fall and accelerating decomposition due to changes in understory light, air/soil temperature, and soil moisture regimes (Lorenz and Lal, 2014). ...
Rhamnus prinoides is a wide spread plant species in of Ethiopia, which is used for cash income, local and commercial beverage preparation and medicinal values. This study was therefore conducted to characterize the provenance and assess traditional management practices of R. prinoides in wag-lasta District. The data collection was done through formal household survey, field observation and inventory. The result showed that 39.6 % of the respondents used leaf color, and 50.5 % of the respondents used leaf thickness to differentiate different types of R. prinoides provenances. Only 9.9 % of the participants were used both leaf color and leaf thickness to identify different provenances of R. prinoides. According to 60 % of the respondents, R. prinoides flowers between September and November. To harvest R. prinoides, respondents used different techniques including picking leaves and/or stems with hand or sickle. Regarding, traditional management practice of R. prinoides, the major respondents (81.5%) explained that they were using hoeing, weeding, watering, mulching, manure, organic fertilizer (compost). Only 17.6% of them uses all including inorganic fertilizer (DAP). Extension support is important to enhance the productivity of R. prinoides plant, better knowledge and skill of the management is requiredcompared to the traditional management practiced in the study area.
Key words: Harvesting technique, Provenance, Propagation method, Management practice.
... Thinning and pruning of trees may reduce SOC sequestration by reducing litter fall and accelerating decomposition due to changes in understory light, air/soil temperature, and soil moisture regimes (Lorenz and Lal, 2014). ...
In Ethiopia, different restoration efforts including exclosures have been implemented to reduce or reverse degraded lands. Exclosure is one of the most common practices used to enhance soil fertility and diversity of degraded areas for centuries. This study aimed to assess the effects of exclosure on woody species diversity in semi-arid region of Sekota. A total of 63 (20 m × 20 m) nested plots were used to collect the necessary data in exclosure and non-exclosures (grazing land). Non-exclosure (grazing land) was used as a control for comparison purpose. In each plot, four replicated quadrats were used to measure the parameters for saplings (5 m × 5 m) and seedlings (2 m × 2 m). The result showed that 35 woody species, which representing 21 families and 29 genera were found in exclosures. However, 19 woody species representing 13 families and 13 genera were recorded in non-exclosures. Acacia etbaica was the most dominant species both in the exclosure and control. The Shannon and Simpson indices were significantly higher (1.77 ± 0.46 and 0.80 ± 0.49) in exclosure than grazing land (1.39 ± 0.46 and 0.74 ± 0.52). Exclosures have shown higher regeneration status than grazing land. The result suggests that exclosures have played a great role for restoration of vegetation diversity in degraded lands. Further techniques should be integrated in exclosures to hasten regeneration thereby to facilitate the restoration.
Keywords: Dryland, abundance, diversity, population structure and regeneration
... Soil total organic carbon (TOC) dynamics are regulated by elemental stoichiometry [5,6]. As the dominant constituent of SOM, TOC represents one of the most commonly determined soil attributes. ...
Soil elemental stoichiometry, expressed as the ratios of carbon (C), nitrogen (N), and phosphorus (P), regulates the biogeochemical processes of elements in terrestrial ecosystems. Generally, the soil C:N:P stoichiometry characteristics of agricultural ecosystems may be different from those of natural ecosystems, with distinct temporal and spatial variations along with the alterations of agricultural land use types (LUTs). The balance of soil C, N, and P reflected by their stoichiometry is primarily important to microbial activity and sustainable agricultural development. However, information on soil stoichiometric changes after long-term alterations in land use is still lacking. We characterized the temporal and spatial changes in soil elemental stoichiometry coupled with alterations in agricultural LUTs in the Taihu Lake basin. By using the ArcGIS method and meta-data analysis, our results showed that the C:N, C:P, and N:P ratios of agricultural soil in the Taihu Lake basin were much lower than the well-constrained values based on samples from forest, shrubland, and grassland at a global scale. Generally, these elemental ratios in soils increased from the 1980s to the 2000s, after experiencing changes from agricultural to other land use. The soil C:N:P stoichiometry may have maintained the increasing trend according to the meta-data analysis from the 341 peer-reviewed publications since 2010. Nevertheless, different regions showed inconsistent change patterns, with the Tianmu Mountain area surrounding the downstream of the Taihu Lake basin experiencing a reduction in those ratios. The changes in LUTs and their corresponding management practices were the major drivers shaping the spatial and temporal distributions of soil C:N, C:P, and N:P. Paddy soil generally achieved higher C sequestration potential due to more straw input and a more rapid transfer of straw C into soil C in the upstream of the Taihu Lake basin than other land use types. These results provide valuable information for the agricultural system of intensive cultivation on how their soil elemental stoichiometry characteristics vary temporally and spatially due to the alteration of agricultural land use types.
... They relieve demand from forest resources or conservation areas through a balance between production and protection of natural resources (Bhagwat et al., 2008), they restore degraded land and prevent deforestation (Castro-Nunez, 2018). Agroforestry systems have the potential to sequester atmospheric carbon into soil, thus acting as a land-based sink and helping to mitigate climate change (Abbas et al., 2017;Lorenz & Lal, 2014). It has been reported that agroforestry systems also help consolidate peace by improving livelihoods and by ensuring the provision of long-term ecosystem services as well as socio-ecological resilience to climatic, political and market shocks and stress (Baptiste et al., 2017). ...
... The permanence of these materials (e.g., aromatic, aliphatic, phenolic compounds, lignin, polysaccharides) is not only associated with their intrinsic characteristics, but also with the functional complexity of the system, meaning the interaction between edaphic and climatic characteristics (Powers et al. 2009;Lehmann and Kleber 2015;Lehmann et al. 2020). Thus, the cacao and rubber AFSs, pure rubber plantation and forest can influence the amount of litter, as well as the heterogeneity of organic compounds incorporated into the soil (Lorenz and Lal 2014). ...
Agroforestry systems (AFS) promote a continuous deposition of organic material in the soil via litter and roots. Litter has a diversity of organic compounds with different chemical complexities, and which act as raw materials in forming and maintaining soil organic carbon. The objective of this study was to characterize the chemical composition of litter provided in soils under natural forest, rubber tree and cacao AFSs of different ages (old and young AFS) and a pure rubber plantation. Litter samples were collected in each of the AFSs in both cacao and rubber lines. The determination of functional groups was performed by Diffuse Reflectance Fourier Transform Infrared Spectroscopy. The results showed that the old AFS (cacao line) mainly presented bands associated with aromatic compounds (1600−1500 cm⁻¹), while the highest absorbance intensity observed in the old AFS (rubber line) was in the range of 1097−1040 cm⁻¹, attributed to the presence of cellulose. The main difference observed between cacao line and rubber line in the young AFS was the presence of polysaccharide functional groups (1380−1240 cm⁻¹) in the rubber line. The similarity between the young AFS cacao line and rubber line, old AFS (rubber line) and the pure rubber plantation can be explained by the presence of phenolic (3690, 3620, 3290 cm⁻¹) and aliphatic (2922 cm⁻¹) compounds. The natural forest was dissimilar to the other systems mainly in the bands around 1051−1040 cm⁻¹ and 918 cm⁻¹, suggesting a forest litter with a predominance of less complex chemical structures.
... It is a crucial leader of terrestrial C sequestration containing about 12% of the global terrestrial C (Dixon 1995). The roots of forest tress and perennial crops penetrate deeper subsurface horizons, thus placing SOC at deeper horizons far away from the range of tillage implements (Lorenz and Lal 2014). Estimating the C sequestration potential of agroforestry systems under varied ecological and management environments ranged from 0.29 to 15.21 Mg ha À1 year À1 in aboveground plant biomass and 30 to 300 Mg ha À1 year À1 in belowground plant parts up to a depth of 1.0 m (Nair et al. 2010). ...
Climate change, driven by rising greenhouse gas (GHG) concentrations in the atmosphere, poses serious and wide-ranging threats to human societies and natural ecosystems all over the world. Agriculture and forestry account for roughly one-third of global emissions, including 9 to 14% of GHGs from crop and livestock activities. Due to increasing demand based on human population and income growth and dietary change, GHG emissions are likely to increase by about 76% by 2050 relative to the levels in 1995. Nitrous oxide (N2O) and methane (CH4) are the major GHGs contributed from the agricultural sector, contributing 50 and 70%, respectively, to the total levels. However, carbon dioxide (CO2) emissions are mainly contributed by a change in land use patterns and decomposition of organic materials. Global emission pathways that would limit warming to 1.5 °C or less, in line with the Paris Agreement’s temperature goal, depend on significant reductions in agricultural GHGs (N2O and CH4) as well as net zero CO2 emissions from fossil fuels. As the agricultural sector mainly contributes to N2O and CH4, 4.8 Gt CO2-eq reduction in direct global agricultural non-CO2 emissions below baseline by 2050 is needed. These ambitious targets of mitigation pathways present an enormous challenge, and accomplishment of these goals is only possible by the implementation of effective GHG mitigation strategies to the agricultural sector. Mitigation measures in the agricultural sector include increasing C sequestration as well as reduction in the GHGs from livestock and agricultural processes. In this chapter, we discussed mitigation strategies for GHG emissions from the agricultural sector at the global scale.KeywordsAgricultural systemsCarbon sequestrationClimate changeEcosystemsGreenhouse gasLivestock
... ;https://doi.org/10.1101https://doi.org/10. /2022 It would be possible to increase C sequestration of the conservation scenario further by increasing C inputs, for instance by shifting towards more complex systems such as agroforestry (Lorenz and Lal, 2014). In their review, Cardinael et al. (2018) indicate that converting an arable system to a silvo-arable system yielded mean annual C sequestration rates of 0.21, 0.28, and 1.12 t/ha in SOC, below-ground biomass, and above-ground biomass, respectively. ...
Urgent action is needed to ensure humanity’s future under climate change. Agriculture faces major challenges as it is both influenced by and contributes to climate change. Conservation agriculture reduces greenhouse gas (GHG) emissions and sequesters carbon (C) in the soil due to practices such as reduced tillage and planting of cover crops. This study assessed effects of an innovative conservation agriculture popcorn ( Zea mays ) and wheat ( Triticum aestivum ) crop rotation in south-western France on soil C sequestration, GHG emissions and several environmental impacts. Two complementary approaches were used: i) a comparison based on field data and expert judgement to assess short-term effects and ii) modelling of three scenarios to quantify long-term outcomes. In both approaches Life cycle assessment (LCA) was used to compare popcorn and wheat rotations. The conventional rotation used ploughing, and its soil was bare between wheat harvest and popcorn sowing. Conservation agriculture used reduced tillage, cover crops, and compost of green waste. Impacts of compost production were allocated mainly to its waste treatment function, based on waste treatment cost and compost price. Simulation modelling of soil C was used to estimate the amount of C sequestered by the conservation and conventional crop rotations. LCA was combined with soil C modelling over 100 years to assess the long-term climate change impact of three scenarios for the popcorn and wheat rotation. Mean annual C sequestration and net climate change impact were -0.24 t/ha and 3867 kg CO 2 -eq./ha, respectively, for the conventional rotation and 0.91 t/ha and 434 kg CO 2 -eq./ha, respectively, for the conservation rotation. The climate change impact of the conservation rotation depended strongly on the allocation of composting impacts between the waste treatment and compost production functions. Compared to the conventional rotation, the conservation rotation had a lower marine eutrophication impact (−7%) but higher impacts for terrestrial acidification (+9%), land competition (+3%), and cumulative energy demand (+2%). Modelling over 100 years revealed that at near soil C equilibrium, a conventional scenario lost 9% of soil C, whereas conservation agriculture scenarios gained 14% (only cover crop) and 26% of soil C (cover crop + compost). Conservation agriculture resulted in soil C sequestration over several decades, until a new soil C equilibrium was reached.
Highlights
Conservation and conventional popcorn and wheat crop rotations were compared
Coupling of LCA and soil carbon modelling allowed for comprehensive assessment
Conservation agriculture sequestered carbon in the soil
Conservation agriculture strongly reduced climate change impact
Compost impact-allocation choices strongly influenced potential impacts
... Ici plusieurs points d'ancrage me semblent intéressants : l'expertise chimique des complexes organo-métalliques (Ni, Cr, Mg, Cu) dans les sols et les eaux, et la mise au point récente d'une méthode originale de séquestration du carbone dans les sédiments, potentiellement applicable au sol (Gunkel-Grillon P., 2015). Enfin, je suis en liaison dans le cadre de l'édition avec le Professeur Rattan Lal (Stavi et Lal, 2013, Lorenz et Lal, 2014, directeur du centre de management et de séquestration du carbone de l'université de l'Ohio, qui a accepté le principe d'une future collaboration. ...
Les effets du changement climatique pourraient être fortement atténués si l'on stockait davantage de carbone dans les sols. Or le rôle des minéraux pour la préservation de la matière organique des sols est peu connu. Ce projet proposait d'identifier et d'étudier la stabilité des complexes organo-minéraux au niveau moléculaire.
... ASP systems improve the chemical, physical, and biological properties of soil, prevent erosion, promote carbon sequestration, conserve water resources, and increase biodiversity, in addition to providing several technical, economic, and social benefits (Muller et al. 2011;Lorenz and Lal 2014;Freitas et al. 2020). They also help optimize land use and increase agricultural productivity (Alves et al. 2017). ...
Agrosilvopastoral (ASP) systems are sustainable production models for expansion in Brazil, and selecting the appropriate tree species is a fundamental requirement of ASP systems and a function of edaphoclimatic conditions. Therefore, this study aimed to analyze the biotic and abiotic factors that influence the initial growth and adaptation of two Eucalyptus genotypes (Eucalyptus cloeziana and Eucalyptus urograndis) intercropped with Sorghum bicolor and Urochloa brizantha in ASP systems in the Brazilian Cerrado. The damages, weaknesses, survival rates, diameters at soil height and breast height, and the total height of trees were evaluated over four years, considering rainy and dry periods. The data were analyzed using a correlation matrix and analysis of variance. Trigona spinipes and termites were the main biotic factors that caused damage and weakness in the E. cloeziana and E. urograndis genotypes, respectively. Eucalyptus urograndis showed a higher total height and diameter at breast height than E. cloeziana at 450, 630, 1020, and 1320 days after transplanting. Eucalyptus cloeziana had the highest survival rate (80.6%), whereas E. urograndis was more tolerant to water stress. Thus, even with severe termite attacks after sorghum harvest, E. urograndis was better adapted to the edaphoclimatic conditions in the present study and it is recommended in ASP systems in sites with high temperature and irregular rainfall distribution.
... This tree density is easily exceeded in most tropical regions (Torres et al., 2017). Carbon storage in tree biomass is highly significant in silvopastoral systems, but significant SOC stock change has also been frequently reported in these and other regions of the world (Lorenz and Lal, 2014). ...
In this chapter, we will discuss the effect of different grassland management practices on greenhouse gas (GHG) emissions and soil organic carbon (SOC) sequestration. This includes comparison of grasslands with arable croplands, the role of N fertilization, and grazing strategies. Special emphasis will be given to grasslands in rotation with cropping systems and integration with timber systems to improve sustainable management and SOC sequestration.
... Third, reducing the share of residue burning and improved manure recycling could further increase C inputs. Finally, other carbon accumulating practices, such as the cultivation of cover crops (Poeplau and Don, 2015;Porwollik et al., 2022) and agroforestry (Lorenz and Lal, 2014), could increase total C sequestration on cropland. ...
Soil organic carbon (SOC), one of the largest terrestrial carbon (C) stocks on Earth, has been depleted by anthropogenic land cover change and agricultural management. However, the latter has so far not been well represented in global C stock assessments. While SOC models often simulate detailed biochemical processes that lead to the accumulation and decay of SOC, the management decisions driving these biophysical processes are still little investigated at the global scale. Here we develop a spatially explicit data set for agricultural management on cropland, considering crop production levels, residue returning rates, manure application, and the adoption of irrigation and tillage practices. We combine it with a reduced-complexity model based on the Intergovernmental Panel on Climate Change (IPCC) tier 2 method to create a half-degree resolution data set of SOC stocks and SOC stock changes for the first 30 cm of mineral soils. We estimate that, due to arable farming, soils have lost around 34.6 GtC relative to a counterfactual hypothetical natural state in 1975. Within the period 1975–2010, this SOC debt continued to expand by 5 GtC (0.14 GtC yr−1) to around 39.6 GtC. However, accounting for historical management led to 2.1 GtC fewer (0.06 GtC yr−1) emissions than under the assumption of constant management. We also find that management decisions have influenced the historical SOC trajectory most strongly by residue returning, indicating that SOC enhancement by biomass retention may be a promising negative emissions technique. The reduced-complexity SOC model may allow us to simulate management-induced SOC enhancement – also within computationally demanding integrated (land use) assessment modeling.
... The nutrient use efficiency will be enhanced due to the increased absorption and availability of soil with high OM and an active deep root system [19]. Additionally, the increased microbial diversity due to OM addition [20] probably provides mycorrhizae, releasing P and making it accessible to crops [21]. The nitrogen fixing in the trees enhances the amounts of soil and N cycling through the decomposed leaf litter and improves the long-term soil N through OM additions. ...
Agroforestry integrates woody perennials with arable crops, livestock, or fodder in the same piece of land, promoting the more efficient utilization of resources as compared to monocropping via the structural and functional diversification of components. This integration of trees provides various soil-related ecological services such as fertility enhancements and improvements in soil physical, biological, and chemical properties, along with food, wood, and fodder. By providing a particular habitat, refugia for epigenic organisms, microclimate heterogeneity, buffering action, soil moisture, and humidity, agroforestry can enhance biodiversity more than monocropping. Various studies confirmed the internal restoration potential of agroforestry. Agroforestry reduces runoff, intercepts rainfall, and binds soil particles together, helping in erosion control. This trade-off between various non-cash ecological services and crop production is not a serious constraint in the integration of trees on the farmland and also provides other important co-benefits for practitioners. Tree-based systems increase livelihoods, yields, and resilience in agriculture, thereby ensuring nutrition and food security. Agroforestry can be a cost-effective and climate-smart farming practice, which will help to cope with the climate-related extremities of dryland areas cultivated by smallholders through diversifying food, improving and protecting soil, and reducing wind erosion. This review highlighted the role of agroforestry in soil improvements, microclimate amelioration, and improvements in productivity through agroforestry, particularly in semi-arid and degraded areas under careful consideration of management practices. Citation: Fahad, S.; Chavan, S.B.; Chichaghare, A.R.; Uthappa, A.R.; Kumar, M.; Kakade, V.; Pradhan, A.; Jinger, D.; Rawale, G.; Yadav, D.K.; et al. Agroforestry Systems for Soil Health Improvement and Maintenance. Sustainability 2022, 14,
... SPSs have a positive effect on carbon sequestration and, consequently, on GHG emission mitigation, since they increase above-and below-ground biomass and reduce soil erosion (Lorenz and Lal 2014). In dry tropical conditions in Mexico, López-Santiago et al. (2019) reported that SPSs contained more aboveground biomass (approximately 40 Mg dry matter (DM) ha -1 ) than grass systems (< 10 Mg DM ha -1 ), and greater below-ground biomass (approximately 16 Mg DM ha -1 ) than deciduous tropical forest and grass systems (approximately 8.4 and 1.4 Mg DM ha -1 , respectively). ...
Papers from the Rural development report 2021
... Our results showed that species mixing had a positive effect on both processes (Fig. 5). On the one hand, mixed planting with deciduous trees increased the aboveground and belowground litter, and the secretion was transported into soils, promoting the formation and accumulation of SOC (Lorenz and Lal, 2014;Chen et al., 2020). On the other hand, the added input of plant root carbon in the soil and declined soil acidity significantly increased the microbial biomass carbon, which directly increased the source of SOC. ...
It is becoming a tendency for multispecies plantations to be promoted worldwide to enhance carbon sequestration and provide better ecosystem services. Soil physicochemical properties and enzymatic activities are critical for tree growth and biogeochemical processes. However, the effects of species mixing on soil properties and enzymatic activities in monoculture plantation forests remain unclear. We conducted a meta-analysis to quantify the effects of species mixing on soil physicochemical properties and enzymatic activities in Chinese fir plantations. We collected 4,620 paired observations from 120 studies. We found that soil physicochemical properties and enzymatic activities increased by 13.97% and 36.34% in species mixing plantations compared to monoculture plantations. Species mixing enhanced soil aeration, water holding capacity, and the total amount and availability of nutrients, increased the soil organic carbon stocks and improved soil nutrient cycling in plantations. The effects of species mixing on soil physicochemical properties and enzymatic activities were negatively correlated with slope, mean annual temperature, and mean annual precipitation but positively correlated with the number of tree species and the proportion of mixed species. In summary, our meta-analysis highlights the positive effects of species mixing on soil nutrient cycling and ecosystem function in Chinese fir plantations and recommends species mixing rather than monoculture plantations for afforestation to support the sustainable and healthy development of forests.
... Inclusion of diverse crop rotations and cover crop mixes in farming systems can improve soil cover, biodiversity and ecosystem functions, such as plant available nutrients, water storage, nutrient use efficiency and crop yield (Lorenz and Lal 2014;Poeplau and Don 2015;Sarker et al. 2018a, b). While deforestation provides wood products to meet the needs of a growing population, there are negative effects of this land use change on ecosystem services such as increase in soil erosion (wind and water), decline of water regulation against floods and landslides, loss of plant biodiversity and a decline in aesthetic and recreational values. ...
Impact of climate change and land use management on soil health can be assessed by some indicators like aggregate stability, soil organic matter, carbon and nitrogen cycling, microbial biomass and activity and microbial fauna and flora diversity. For that purpose, a minimum data set is important for useful quantitative application of soil health concept and starting suitable soil and water conservation measures on farm land, especially on individual plot for assuring sustainable crop cultivation and food security.
... Hedgerows have the potential to sequester SOC [25,[27][28][29] through both increased inputs (e.g., litter deposition and root exudates) [30,31] and reduced losses (e.g., reduced disturbance, lack of irrigation, and erosion control) [32,33]. Quantitative investigations of SOC stocks in deep soil layers and the distribution and dynamics of C sequestration under hedgerows, however, are scarce [28,34,35]. ...
Effective incentivization of soil carbon (C) storage as a climate mitigation strategy necessitates an improved understanding of management impacts on working farms. Using a regional survey on intensively managed farms, soil organic carbon (SOC) concentrations and stocks (0–100 cm) were evaluated in a pairwise comparison of long-term (10+ years) woody hedgerow plantings and adjacent crop fields in Yolo County, CA, USA. Twenty-one paired sites were selected to represent four soil types (Yolo silt loam, Brentwood clay loam, Capay silty clay, and Corning loam), with textures ranging from 16% to 51% clay. Soil C was higher in the upper 100 cm under hedgerows (14.4 kg m−2) relative to cultivated fields (10.6 kg m−2) and at all depths (0–10, 10–20, 20–50, 50–75, and 75–100 cm). The difference in SOC (3.8 kg m−2) did not vary by soil type, suggesting a broad potential for hedgerows to increase SOC stocks. Assuming adoption rates of 50 to 80% across California for hypothetical field edges of average-size farms, and an identical SOC sequestration potential across soil types, hedgerows could sequester 10.8 to 17.3 MMT CO2e, or 7 to 12% of California’s annual greenhouse gas reduction goals.
... Indications were found that rootderived OC inputs are deposited even in deep subsoils as tree roots may grow deeper in agroforestry system compared to forest ecosystems (Cardinael et al., 2015;Germon et al., 2016). Moreover, SOC increases can be attributed to OC inputs of understorey vegetation within tree rows of agroforestry systems as well as increased yields on adjacent agricultural land due to improved microclimate conditions (Cardinael et al., 2018;Lorenz and Lal, 2014). Although increased OC inputs may be the most important factor for OC sequestration in agroforestry systems, other processes leading to better microbial functioning due to enhanced soil quality (Guillot et al., 2021), and/or an increased retention of OM through reduced soil disturbance and erosion and reduced decomposition of recalcitrant tree litter may be relevant. ...
Organic carbon sequestration is delineated from the different mechanisms underlying the storage of organic matter in mineral soils. The scene is set with definitions of the major terms within the complex of organic matter formation in soils, followed by describing the types of organic matter entering the soil and the major processes during turnover and the protective mechanisms leading to organic matter storage in soils. Detritusphere and rhizosphere are identified as soil compartments with high and specific organic matter input. From the process complex of OM degradation and binding, the potential of different soils for sequestering organic carbon is delineated and its limitations discussed with regard to the possibility of C saturation of mineral soils. In the light of these considerations, soil management options are deduced either by increasing organic carbon inputs to the soil by improved land use/management practices or by decreasing organic carbon outputs.
... For example, shelterbelts have been shown to increase the soil microbial biomass and diversity in adjacent farmland [27,28], which is considered a memory effect and could be maintained for decades after environmental changes [29][30][31][32]. The post-cutting shelterbelt was called the "ghost shelterbelt" [23] because it still had considerable organic carbon stock inheritance in the adjacent farmland that was conducive to crop growth [33][34][35]. Thus, regarding the crop yield increase, the post-cutting shelterbelt should have a legacy effect due to lingering effects on soil composition. ...
Shelterbelts (or windbreaks) can effectively improve the microclimate and soil conditions of adjacent farmland and thus increase crop yield. However, the individual contribution of these two factors to yield changes is still unclear since the short-term effect from the microclimate and the accumulated effect from the soil jointly affect crop yield. The latter (soil effect) is supposed to remain after shelterbelt-cutting, thus inducing a post-cutting legacy effect on yield, which can be used to decompose the shelterbelt-induced yield increase. Here, we develop an innovative framework to investigate the legacy effect of post-cutting shelterbelt on corn yield by combining Google Earth and Sentinel-2 data in Northeastern China. Using this framework, for the first time, we decompose the shelterbelt-induced yield increase effect into microclimate and soil effects by comparing the yield profiles before and after shelterbelt-cutting. We find that on average, the intensity of the legacy effect, namely the crop yield increment of post-cutting shelterbelts, is 0.98 ± 0.03%. The legacy effect varies depending on the shelterbelt–farmland relative location and shelterbelt density. The leeward side of the shelterbelt-adjacent farmland has a more remarkable legacy effect compared to the windward side. Shelterbelts with medium–high density have the largest legacy effect (1.94 ± 0.05%). Overall, the legacy effect accounts for 47% of the yield increment of the shelterbelt before cutting, implying that the soil effect is almost equally important for increasing crop yield compared to the microclimate effect. Our findings deepen the understanding of the mechanism of shelterbelt-induced yield increase effects and can help to guide shelterbelt management.
... Representación conceptual de los procesos que influyen en la fijación, recambio y almacenamiento de carbono en sistemas silvopastoriles comparado con un sistema de pasto en monocultivo El suelo contiene casi el triple de carbono que toda la biomasa de la vegetación mundial. En la actualidad, este reservorio es el que almacena más carbono de la atmosfera (Lorenz y Lal, 2014). En México, el cambio de uso de suelo de vegetación nativa a potreros abiertos ha causado un agotamiento de carbono orgánico de suelo (COS) hasta en un 30% (Aryal et al., 2018b). ...
El trabajo colectivo es el sello que hemos impuesto en la publicación de los últimos tres libros que coordinamos y en esta cuarta propuesta no puede ser la excepción. Además, por el tema elegido que combina las tecnologías de tipo agroforestal como herramienta para enfrentar el cambio climático, en México, resulta de vital importancia mantener ese enfoque. Esto permitió que participaran 66 autores adscritos a 19 instituciones de diferentes regiones o estados del territorio mexicano. El enfoque desarrollado implicó la propuesta de tecnologías silvopastoriles o agrosilvopastoriles que evidenciaran mecanismos de adaptación, mitigación o ambas opciones para enfrentar el cambio climático. Al respecto, el primer capítulo es introductorio para entender a la agroforestería y su aportación a la adaptación y mitigación al cambio climático, en México. El resto de los capítulos se dividen de la siguiente manera: siete sobre adaptación, en donde cuatro son de tipo agrosilvopastoriles y tres silvopastoril; en relación a la mitigación sólo se presentaron dos que corresponden a tecnologías silvopastoriles y, fi¬nalmente, con la combinación de adaptación y mitigación se lograron conjuntar cinco tecnologías, una de tipo agrosilvopastoril y cuatro silvopastoril. Por lo tanto, este libro es una muestra de lo que existe en México sobre el tema y esperamos que sirva de incentivo para que otros colegas e instituciones aborden este tipo de propuesta y muestren sus aportes en tecnologías agroforestales.
... Perennial grasses, such as Brachiaria, add more C because of the activity of their root system (BAPTISTELLA et al., 2020; Table 2 -Mean indicator scores of the chemical, physical, and biological components under native vegetation (NV), pasture (PAST), and silvopastoral system (SPS) in the 0-10, 10-20, and 20-30 cm soil depth in the Colombian Amazon * Means within columns at each site and soil depth followed the same letter do not differ signifi cantly according to Tukey's test (p < 0.05), ns: not signifi cant MCSHERRY; RITCHIE, 2013). In the same way, SPS soils have higher capacity to sequester C than NV soils (KAY et al., 2019;OLAYA-MONTES et al., 2020) by adding C through litter deposition, root systems of grasses, and cattle manure (LORENZ; LAL, 2014;ROCHA JUNIOR et al., 2014). Several studies have pointed out the role of agroforestry systems in sequestering C in soil and biomass (DOLLINGER; JOSE, 2018; HOOSBEEK; REMME; RUSCH, 2018). ...
Monitoring the influence of livestock systems’ on soil quality (SQ) in the Colombian Amazon region is important to ensure the sustainability of those agroecosystems. Here we used the Soil Management Assessment Framework (SMAF) to assess the SQ responses to land-use change associated with the adoption of silvopastoral systems (SPS) at two study sites in the Colombian Amazon region. A chronosequence formed by three land-use systems, reflecting the typical land transition performed in the region, was established at each study site: i) native vegetation (NV), ii) pasture (PAST), and iii) SPS. Soil samples were collected at 10 cm deep increments until reaching 30 cm deep. Then soil pH, potassium, available phosphorus, microbial carbon, soil organic carbon, and bulk density were measured. In addition, data from Visual Evaluation of Soil Structure (VESS) were correlated. Data were interpretated using SMAF algorithms, and a Soil Quality Index (SQI) was calculated. Our data showed an SQ degradation due to land-use change from NV to PAST, with soils reducing their capacity of soils function from 0.72 to 0.62. The establishment of SPS over extensive PAST restored soil quality (SQI = 0.69) compared to PAST (both sites), even reaching similar SQI values to those observed in NV at site 1. The SMAF showed to be a potential tool to monitor the SQ in low-fertility soils from the Colombian Amazon region. The VESS scores were also correlated with SMAF - scores, proving to be a simple and complementary tool for farmers to monitor SQ in the Amazon region.
Key words
Integrated farming systems; Agroforestry systems; Livestock; VESS; Ecosystem services
... Agroforestry offers a lot of potential for preserving and enhancing land-based carbon sinks in degraded areas. Agroforestry may play a significant role in lowering vulnerability, boosting the resilience of farming systems, and protecting families from climate threats by increasing the building of soil organic matter and by producing biomass that can capture more CO 2 from the air (Lorenz and Lal 2014). Nowadays, sequestering carbon via a tree-based method is viewed as a lucrative business prospect for carbon trading. ...
The present study was conceptualized in 2012 under the Morena district of Madhya Pradesh's Niche Area of Excellence of Research Work Plan to control and reclamation of ravines and their management for sustainable livelihood security. To assess the contribution of various plantations after 10 years, the current study, which runs from 2020-2021 to 2021-2022, was done. Several types of native fruit trees and forest trees were assessed on various uneven and flat areas of ravine ground such as Moringa oleifera, Terminalia arjuna, Azadirachta indica, Gmelina arborea, Millettia pinnata, Albizia lebbeck, Acacia nilotica, Dalbergia sissoo, and Justicia adhatoda. The pooled analysis effect of the carbon content of the tree (pounds/plant) varies within different tree species during 2020-2021 to 2021-2022. The results revealed that the highest carbon weight of the tree was recorded for Moringa oleifera (2753.02 pounds/plant), followed by Albizia lebbeck (1637.58 pounds/plant), Azadirachta indica (768.94 pounds/plant), Acacia nilotica (704.23 pounds/plant), Dalbergia sissoo (698.84 pounds/plant), Terminalia arjuna (356.38 pounds/plant), Millettia pinnata (282.65 pounds/plant) and Gmelina arborea (147.93 pounds/plant). While the lowest carbon weight of the tree was recorded in Justicia adhatoda (4.59 pounds/plant).
... The relationship between biomass carbon (BC) stock and soil organic carbon (SOC) stocks of AF systems can vary depending on different factors. Considering vegetation as one of the many factors influencing SOC stocks [66,67], studies conducted in wide areas of the tropics showed that a consistent addition of tree/shrub prunings and their root turnover over the years have contributed to the accumulation of SOC [8]. Results that support the contribution of biomass C to the SOC were reported from different countries. ...
The role of agroforestry systems in providing ecosystem services is very crucial. The most significant increase in carbon (C) storage is often achieved by moving from lower biomass land-use systems to tree-based systems like agroforestry (AF). However, estimation of carbon stocks in indigenous agroforestry systems of South-eastern Rift- valley landscapes, Ethiopia the data are scarce. The study was aimed to investigate the biomass, biomass carbon (BC), and soil organic carbon (SOC) stock of Enset based, Enset-Coffee based, and Coffee-Fruit tree-Enset based agroforestry systems. Comparison of SOC stock of agroforestry systems against their adjacent monocropping farms was also investigated. The study was conducted in three selected sites of the Dilla Zuria district of Gedeo zone. Twenty farms (total of 60) representative of each AF system were randomly selected, inventoried and biomass C stocks estimated. Ten adjacent mono-cropping farms which were related to each AF system were selected in a purposive manner for comparison of SOC stock. Inventory and soil sampling were employed in the 10×10 m farm plot. The mean aboveground biomass ranged from 81.1 t ha-1 to 255.9 t ha-1 and for belowground biomass from 26.9 t ha-1 to 72.2 t ha-1. The highest C stock was found in Coffee-Fruit tree-Enset based (233.3±81.0 t ha-1), and the lowest was in Coffee-Enset based agroforestry system (190.1±29.8 t ha-1). The result showed that SOC stocks were not statistically significant between the three AF systems, although they showed a significant difference in their BC stock. The AF systems' C stocks are substantially higher than those reported for tropical forests and other AF systems. The SOC of AF systems was significantly higher than the ones for the adjacent monocropped farms. Therefore, it is possible to deduce that AF systems are storing significant amount of C and contributing to climate change mitigation.
... Im bodenwissenschaftlichen Kontext bezeichnet der Begriff C-Sequestrierung die langfristige Festlegung von CO2 im Boden(Lorenz et al. 2014). Diese Langfristigkeit der C-Bindung -über Jahrhunderte oder Jahrtausende -stellt gegenüber einer eher temporären Akkumulation (z.B. ...
The carbon reduction potential and accounting principles in agroforestry outlined in this article cover four sectors – comparable to other land use-based strategies. 1) above-ground biomass, 2) below-ground biomass, 3) the soil, and 4) the up- and downstream sector. The recommendations cover ten frequently discussed topics and concerns, namely 1) additionally, 2) quantifiability, 3) displacement effects, 4) contribution to food security, 5) additional emissions, 6) longevity and durability, 7) traceability, 8) transaction and opportunity costs, 9) synergies and compromises with other goals, and 10) security, trust and transparency. If the recommendations developed are taken into account, the authors conclude that the climate protecting and mitigation services of agroforestry in the form of carbon reduction potential can and should be rewarded by climate or carbon certificates. On the one hand, this could be seen as an innovative and promising way of financing future agroforestry systems; on the other hand, it must be ensured that the measures meet minimum scientific and social requirements. If planned scientifically sound, reliable, transparent and ethically just, there is a good chance to create with climate certificates for agroforestry some contributing solutions for EUs ambitious climate target plan, a 55 percent greenhouse gas reduction by 2030 compared to 1990.
... Preservation and restoration of soil humus as the main storage of carbon, as well as nitrogen, phosphorus, sulfur and other plant nutrients is a necessary condition for sustainable agriculture (Fu et al, 2020). Information that characterizes the amount of organic matter in the soil becomes a decisionmaking tool not only in agriculture, but also is crucial in mitigating the global effects of climate change, etc. (Lorenz and Lal, 2014). ...
To get additional tools for the assessment of carbon sequestration, along with the visual assessment of soil coloration with the applying of A. H. Munsell’s atlas, the analysis of color and spectral characteristics of soil using portable colorimeter NixPro and reflectometer Our Sci Reflectometer was carried out in this study. Elemental analysis of soil samples using X-ray fluorescence analysis was performed and the content of organic carbon was estimated. The spectral range of reflected light, which correlates most with the content of organic soil substance, was singled out. Based on the data, received by methods of reflectometry and colorimetry, prognostic regression models were constructed. A multiple linear regression equation with a statistically authentic luminosity predictor (L*) (R2=0.61) was obtained. It allows describing the link between the content of the organic substance in the studied soils and the parameters of the color setting system CIELab, as well as the equation describing 69 % of the data link dispersion between the integrated reflection coefficient and the organic carbon content of the soil. The link between the integral reflection coefficient and the total organic substance content was found. The most correlated spectral range with the content of organic substance – 500–632 nm was singled out. Regression models, which were based exclusively on the spectral data of pre-treated H2O2 soils, increased their predictability by 8–10 %. Approaches that can complement the tools for rapid determination of the organic carbon content in the soil were presented in the work. Researchers are expanding their arsenal of technical support for estimation of color or spectral coefficients of light reflection, based on which it is possible to conduct geospatial analysis and determine the content of the organic substance in low-humus soils with a probability of 69 %.
... A mature and extensive review literature has reported the general effects of land use change and forest management on SOC (e.g., Certini, 2005;Dignac et al., 2017;James and Harrison, 2016;Jandl et al., 2007;Mayer et al., 2020;Post and Kwon, 2000;Smith et al., 2016). Numerous review papers have quantified the direction, magnitude, and variability in management effects upon SOC, as well as their drivers at broad scales (Laganiere et al., 2010;Lorenz and Lal, 2014;Nave et al., 2010;Thiffault et al., 2011). Nevertheless, these papers that have contributed so much to our foundational understanding consistently identify a substantial knowledge gap between broad syntheses and site-level studies. ...
Evidence-based forest carbon (C) management requires identifying baseline patterns and drivers of soil organic carbon (SOC) stocks, and their responses to land use change and management, at scales relevant to landowners and resource professionals. The growth of datasets related to SOC, which is the largest terrestrial C pool, facilitates use of synthesis techniques to assess SOC stocks and changes at management-relevant scales. We report results from a synthesis using meta-analysis of published studies, as well as two large databases, in which we identify baseline patterns and drivers, quantify influences of land use change and forest management, and provide ecological context for distinct management regimes and their SOC impacts. We conducted this, the fourth in a series of ecoregional SOC assessments, for the South Atlantic States, which are disproportionately important to the national-scale forest C sink and forest products industry in the U.S. At the ecoregional level, baseline SOC stocks vary with climatic, topographic, and soil physical factors such as temperature and precipitation , slope gradient and aspect, and soil texture. Land use change and forest management modestly influence SOC stocks. Reforestation on previously cultivated lands increases SOC stocks, while deforestation for cultivation has the opposite effect; for continuously forested lands, harvesting is associated with SOC increases and prescribed fire with SOC declines. Effects of reforestation are large and positive for upper mineral soils (+30%) but not detectable in lower mineral soils. Negative effects of prescribed fire are due to significant C losses from organic horizons (-46%); fire and harvest have no impacts on upper mineral soils but both increase SOC in lower mineral soils (+8.2 and +46%, respectively, with high uncertainty in the latter). Inceptisols are generally more negatively impacted by prescribed fire or harvest than Ultisols, and covariance between inherent factors (including soil taxonomy) and management impacts indicates how interior vs. coastal physiographic sections differ in their management regimes and SOC trends. In the cooler, wetter, topographically rugged interior hardwood forests, which have larger baseline SOC stocks, prescribed fire and even light harvesting generally decrease SOC; in contrast, intensively managed coastal plain pine plantations begin with small initial SOC stocks, but exhibit rapid gains over even a single rotation. This covariance between place (physiography) and practice (management regime) suggests that distinct approaches to forest C management may be complementary to other ecological or production goals, when implemented as part of wider (e.g., state-level) forest C or climate policy.
Several agroforestry systems prevail in different agro-ecological zones of Pakistan, and cover a remarkable area of 19.3 million hectares. They not only play an important role in slowing down CO2 emissions, but also contribute to mitigating climate change. However, in many regions, the relevant effect of agroforestry systems on overall carbon (C) stock and their reliance on various factors are quite unidentified. This study was planned to assess the biomass accumulation and C stocks of different commonly practiced agroforestry systems (boundary, bund, scattered, agri-horticulture) and their constituent land use types (tree + cropland) through a non-destructive approach (allometric equations) in a semi-arid region of Punjab, Pakistan. The results showed that the highest plant biomass (87.12 t ha−1) increased by 46%, 17%, 78%, and 339%, and C stock (42.77 t ha−1) increased by 49.51%, 20%, 82%, and 361% in the boundary planting system compared to the bund, scattered, agri-horti and sole cropland, respectively. The soil organic carbon (SOC) stock at all three depths, 0–15 cm, 15–30 cm & 30–45 cm, was found in the following order: boundary planting system > bund planting system > agri-horti system > scattered planting system > agricultural system, with a maximum in the boundary planting system and minimum in the sole cropping system at all three depths. Overall, the total C stock of the ecosystem’s vegetation + soil C (0–30 cm) in the forested area was 275 t ha−1, equating to 37 t ha−1 in the agricultural system alone. Our results highlighted that agroforestry systems have the highest potential for C sequestration. We suggest that research and investment in agroforestry systems can be a successful way for Pakistan to achieve some of its climate change mitigation goals.
In this study, a typical apple–soybean intercropping system was used to analyze the effects of different soil water and heat regulation modes on the spatial distribution of the soil water content (SWC), photosynthetic physiological characteristics, and growth. Three maximum irrigation levels [50% (W1), 65% (W2), and 80% (W3) of field capacity (FC)] and two mulching intervals [from seedling to podding stage (M1) and during the full stage (M2) of soybeans] were tested. The results showed that the SWC of W3M2 was the highest, while the W2M1 and W1M2 treatments used more deep soil water. Irrigation increased the chlorophyll content, net photosynthesis, and transpiration rate of leaves in the agroforestry system. In addition, the net photosynthetic rate of leaves under the W2 irrigation level increased after mulch removal in the later growth stage. At W1 and W2 irrigation levels, the soybean yield of half-stage mulching was 0.85–15.49% higher than that of full-stage mulching. Multiple regression analysis showed that grain yield under the W3M2 treatment reached the maximum value of the fitting equation. The photosynthetic rate, water use efficiency, and grain yield under W2M1 reached 71–86% of the maximum value of the fitting equation, with the largest soil plant analysis development value. To effectively alleviate water competition in the apple–soybean intercropping system, our results suggest adoption of the 80% FC upper irrigation limit (W3) combined with soybean M2 treatment in young apple trees–soybean intercropping system during water abundant years. In addition, adoption of the 65% FC upper irrigation limit (W2) combined with the soybean M1 treatment in water deficit years could effectively improve soil water, heat environment, and promote growth.
The main motivation of this study is to prove some novel integral inequalities for geometrically
convex functions. In order to obtain the main findings, we have used some classical inequalities
such as Hölder and Young inequality for certain powers of the functions.
Environmental contamination due to mines disturbs biological and physio-chemical properties of the soil. Literature available discussing environmental contamination and physical disturbances (waste dumps, loss of vegetation, and quarry sites) due to mines was critically evaluated to understand the implication of mines on soil organic matter. The factors responsible for organic matter (OM) degradation are divided into two categories, i.e., major (direct) and minor (indirect). The impacts due to major factors (decrease in OM at the quarry and waste dumping sites) in OM degradation are easy to quantify and directly caused by mines. The conversion of fertile land into quarry and waste dumping sites lead to loss of soil carbon and imbalances the ecosystem structure. The lack of nutrients and organic matter hinders the revegetation process of waste dump sites. The role of minor factors is not easy to quantify (reduction of OM due to land use and land cover change, depletion of water resources, heavy metal contamination, etc.) and indirectly impacts the OM degradation. The heavy metal contamination of neighboring soil retards the growth of plants and decreases the OM turnover. The soil erosion, loss of agricultural lands, deforestation, loss of soil moisture, depletion of water resources, decrease in microbial activities, and land subsidence in the mining region indirectly contribute to OM degradation. The degradation or release of carbon stored in the soil increases CO2 in the atmosphere contributing significantly to climate change. Mines spread in 57,277 km2 across the world and in India mine wasteland covers 2256 km2 of area. The wider spread of mines suggests that the degradation of OM and its contribution to climate change is in significant quantity at the global level. Further research on the degradation of organic carbon in the vicinity of mines and its contribution to climate change is recommended.
Following the Paris agreement in 2015, the European Union (EU) set a carbon neutrality objective by 2050, and so did France. The French agricultural sector can contribute as a carbon sink through carbon storage in biomass and soil, in addition to reducing GHG emissions. The objective of this study is to quantitatively assess the additional storage potential and cost of a set of eight carbon-storing practices. The impacts of these agricultural practices on soil organic carbon storage and crop production are assessed at a very fine spatial scale, using crop and grassland models. The associated area base, GHG budget, and implementation costs are assessed and aggregated at the region level. The economic model BANCO uses this information to derive the marginal abatement cost curve for France and identify the combination of carbon storing practices that minimizes the total cost of achieving a given national net GHG mitigation target. We find that a substantial amount of carbon, 36.2 to 52.9 MtCO2e yr⁻¹, can be stored in soil and biomass for reasonable carbon prices of 55 and 250 € tCO2e⁻¹, respectively (corresponding to current and 2030 French carbon value for climate action), mainly by developing agroforestry and hedges, generalising cover crops, and introducing or extending temporary grasslands in crop sequences. This finding questions the 3–5 times lower target of 10 MtCO2e.yr⁻¹ retained for the agricultural carbon sink by the French climate neutrality strategy. Overall, this would decrease total French GHG emissions by 9.2–13.8%, respectively (reference year 2019).
Agroforestry is a promising land-use system to mitigate water deficiency, particularly in semi-arid areas. However, the belowground microbes associated with crops below trees remain seldom addressed. This study aimed at elucidating the effects of olive agroforestry system (AF) intercropped with durum wheat (Dw), barely (Ba), chickpea (Cp), or faba bean (Fb) on crops biomass and their soil-rhizosphere microbial networks as compared to conventional full sun cropping (SC) under rainfed conditions. To test the hypothesis, we compared the prokaryotic and the fungal communities inhabiting the rhizosphere of two cereals and legumes grown either in AF or SC. We determined the most suitable annual crop species in AF under low-rainfed conditions. Moreover, to deepen our understanding of the rhizosphere network dynamics of annual crops under AF and SC systems, we characterized the microbial hubs that are most likely responsible for modifying the microbial community structure and the variability of crop biomass of each species. Herein, we found that cereals produced significantly more above-ground biomass than legumes following in descending order: Ba>Dw>Cp>Fb, suggesting that crop species play a significant role in improving soil water use and that cereals are well-suited to rainfed conditions within both types of agrosystems. The type of agrosystem shapes crop microbiomes with the only marginal influence of host selection. However, more relevant was to unveil those crops recruits specific bacterial and fungal taxa from the olive-belowground communities. Of the selected soil physicochemical properties, organic matter was the principal driver in shaping the soil microbial structure in the AF system. The co-occurrence network analyses indicated that the AF system generates higher ecological stability than the SC system under stressful climate conditions. Furthermore, legumes' rhizosphere microbiome possessed a higher resilient capacity than cereals. We also identified different fungal keystones involved in litter decomposition and drought tolerance within AF systems facing the water-scarce condition and promoting crop production within the SC system. Overall, we showed that agroforestry reduces cereal and legume rhizosphere microbial diversity, enhances network complexity, and leads to more stable beneficial microbial communities, especially in severe drought, thus providing more accurate predictions to preserve soil diversity under unfavorable environmental conditions.
A large area of the terrestrial land surface is used for livestock grazing. Trees on grazing lands provide and can enhance multiple ecosystem services such as provisioning, cultural and regulating, that include carbon sequestration. In this study, we assessed the above- and belowground carbon stocks across six different land-uses in livestock-dominated landscapes of Mexico. We measured tree biomass and soil organic carbon (SOC) stocks in fodder banks, live fences, pasturelands with dispersed trees, secondary forests, and primary forests from three different geographical regions and compared them with conventional open pasturelands respectively. We also calculated tree diversity indices for each land-use and their similarity with native primary forests. The aboveground woody biomass stocks differed significantly between land-uses and followed the gradient from less diverse conventional open pasturelands to silvopastoral systems and ecologically complex primary forests. The SOC stocks showed a differential response to the land-use gradient dependent on the study region. Multivariate analyses showed that woody biomass, fine root biomass, and SOC concentrations were positively related, while land-use history and soil bulk density showed an inverse relationship to these variables. Silvopastoral systems and forest remnants stored 27–163% more carbon compared to open pasturelands. Our results demonstrate the importance of promoting appropriate silvopastoral systems and conserving forest remnants within livestock-dominated landscapes as a land-based carbon mitigation strategy. Furthermore, our findings also have important implications to help better manage livestock-dominated landscapes and minimize pressures on natural protected areas and biodiversity in the hotspots of deforestation for grassland expansion.
Farmers are adopting different agroforestry practices, but comparative studies between the practices based on ecosystem functions are often ignored. We assessed species composition and carbon stock in two different agroforestry practices (traditional and improved) adopted in the mid-hills of Nepal. We found higher species richness and dominancy of Citrus synenssis (fruit species) in the improved practice, whereas we found higher species evenness, diversity, and dominance of Ficus clavata (fodder species) in the traditional practice. 0.35 of the similarity index between the two practices indicated that there was 65% difference in species number between the two practices. The improved practice had larger trees with higher frequency compared to traditional practice. The carbon inventory reflected that the total carbon stock between the two practices was insignificant, whereas the total biomass carbon was significantly higher in the improved practice than in the traditional practice. Therefore, improvement in traditional practices has the potential to increase biomass and sequester more carbon within the same unit of land. However, maintaining species diversity is a concern in the improved practice. We suggest policymakers and concerned stakeholders for prioritizing improved agroforestry practice and maintain species diversity while designing strategies for agroforestry promotion and climate change mitigation.
Climate-smart agriculture (CSA) includes approaches that help in reducing climatic extremities and agricultural greenhouse gas (GHG) responsible to global warming. CSA also focuses to balanced and reasonable transformations for agricultural practices. Soil is very diversified due to variations in physical and chemical properties, depending upon the quality and quantity of organic matter, redox potential, and pH status of soil, which also significantly impact the population, growth, and activity of microbes. The microorganism as an arbitrate ensures the sustainable
farming by designing effective nutrient cycling strategies and pest control process and minimizing the negative impact of abiotic stress. Therefore, proper managing and development of beneficial microbes can help to achieve sustainable goals and reduce negative effects on the environment. The microbial biofertilizers, biopesticides, and plant growth-promoting rhizosphere bacteria (PGPR) will replace or at least supplement agrochemicals. Soil microbes also provide carbon sinks and help sequester carbon through various processes like the formation of recalcitrant vegetative tissues, bio-products, and different metabolic and biochemical mechanisms that capture CO2 from the atmosphere; capacity of carbonate sedimentation; and formation of stable soil aggregates, which holds up carbon. Microbes contribute to carbon sequestration by the interactions between the amount of microbial biomass, microbial by-products, its community structure, and soil properties, like clay mineralogy, texture, pore-size distribution, and aggregate dynamics. Soil microbes play a role in climate change through decomposition of organic matter in soil. The diversity and population of soil microorganisms are indirectly influenced by changes in microclimate due to its effects on growth of plant and alignment of vegetation. Soil microbes endorse the sustainability of agriculture and effective operation of agroecosystem through precision agriculture under climate-smart agriculture.
Greenhouse gas removal (GGR) technologies can remove greenhouse gases such as carbon dioxide from the atmosphere. Most of the current GGR technologies focus on carbon dioxide removal, these include afforestation and reforestation, bioenergy with carbon capture and storage, direct air capture, enhanced weathering, soil carbon sequestration and biochar, ocean fertilisation and coastal blue carbon. GGR technologies will be essential in limiting global warning to temperatures below 1.5°C (targets by the IPCC and COP21) and will be required to achieve deep reductions in atmospheric CO2 concentration. In the context of recent legally binding legislation requiring the transition to a net zero emissions economy by 2050, GGR technologies are broadly recognised as being indispensable.
This book provides the most up-to-date information on GGR technologies that provide removal of atmosphere CO2, giving insight into their role and value in achieving climate change mitigation targets. Chapters discuss the issues associated with commercial development and deployment of GGRs, providing potential approaches to overcome these hurdles through a combination of political, economic and R&D strategies.
With contributions from leaders in the field, this title is an indispensable resource for graduate students and researchers in academia and industry, working in chemical engineering, mechanical engineering and energy policy.
RESUMEN Vacío del conocimiento: La presencia de leñosas en el cultivo del café (Coffea arabica L.) contribuye a múltiples beneficios en las funciones ambientales, productivas, socioeconómicas, biológicas, etológicas, protectoras, estéticas, entre otras, del cultivo. Sin embargo, en el sur del departamento de Nariño se presenta un limitado conocimiento de los índices de biodiversidad y, por ende, de los bienes y servicios que proveen estos tipos de sistemas productivos al caficultor. Propósito: El objetivo del presente estudio fue comparar 4 tipos de sistemas productivos y caracterizar el dosel de sombra, calcular los índices de diversidad y estimar el porcentaje de sombra para conocer la producción y volumen de madera resultado del asocio de leñosas en sistemas productivos cafeteros de tres municipios de Nariño. Metodología: Se trabajó en cuatro sistemas productivos: T1: café a pleno sol; T2: café y musáceas; T3: café y leñosas multipropósito; T4: café, musáceas y leñosas perennes multipropósito. El estudio se realizó usando un diseño de bloques completos al azar (con tres bloques) y se midió densidad, índices de diversidad, porcentaje sombra, producción y volumen de madera. Resultados y conclusiones: Se registró un total de 359 individuos, distribuidos en 37
Agroforestry is one of the sustainable approaches to land-use management where both agriculture and forestry combine into an integrated production system to get maximum benefits (Kidd and Pimentel, 1992; Nair, 1998). As per ICRAF (International Centre for Research in Agroforestry, now World Agroforestry Centre), '‘agroforestry is a deliberate integration of woody components with agricultural and pastoral operations on the same piece of land either in a spatial or temporal sequence in such a way that both ecological and economic interactions occur between them.'’ Incorporation of the trees under agroforestry systems (AFS) to harvest potential benefits of trees offers a good option under Low Input Sustainable Agriculture (LISA). In fact, it is an age-old practice revived in the recent past with a renewed scientific interest to maintain the sustainability of agroecosystems (Noble and Dirzo, 1997). The revival of agroforestry became inevitable to meet growing demands of increasing population, to compensate forests in the wake of fast increasing rate of deforestation and soil degradation, both in the tropics and temperate regions of the world, and to conserve biodiversity. Agroforestry provides one of the best alternatives for planting trees outside forests. In other words, it is a collective name for sustainable land-use system to get social, economical, and environmental benefits (Sanchez, 1995). It leads to a more diversified and sustainable system than other croplands without trees. Griffith (2000) considers agroforestry as an alternative subsistence farming patterns for conservation and development, particularly in the tropics. Though practiced in the majority of ecoregions, agroforestry is more common in the tropics. According to a report of the World Bank, around 1.2 billion rural people currently practice agroforestry the world over (World Bank, 2004). There are more than 2000 tree species used in agroforestry (Rao et al., 2000). AFS have been classified based on structural, functional, physiognomy, fioristics, socioeconomic, and ecological aspects (Nair, 1993; Ffolliott, 2003). However, classification based on structural components is very common.
Conceptual models suggest that stability and age of organic carbon (OC) in soil depends on the source of plant litter, occlusion within aggregates, incorporation in organo-mineral complexes, and location within the soil profile. Various tools like density fractionation, mineralization experiments, and radiocarbon analyses have been used to study the importance of these mechanisms. We systematically apply them to a range of European soils to test whether general controls emerge even for soils that vary in vegetation, soil types, parent material, and land use. At each of the 12 study sites, 10 soil cores were sampled in 10 cm depth intervals to 60 cm depth and subjected to density separation. Bulk soil samples and density fractions (free light fractions – fLF, occluded light fractions – oLF, heavy fractions – HF) were analysed for OC, total nitrogen (TN), δ<sup>13</sup>C, and Δ<sup>14</sup>C. Bulk samples were also incubated to determine mineralizable OC.
Declining OC-normalized CO<sub>2</sub> release and increasing age with soil depth confirm greater stability of OC in subsoils across sites. Depth profiles of LF-OC matched those of roots, which in turn reflect plant functional types in soil profiles not subject to ploughing. Modern Δ<sup>14</sup>C signatures and positive correlation between mineralizable C and fLF-OC indicate the fLF is an easily available energy and nutrient source for subsurface microbes. Fossil C derived from the geogenic parent material affected the age of OC especially in the LF at three study sites. The overall importance of OC stabilization by binding to minerals was demonstrated by declining OC-normalized CO<sub>2</sub> release rates with increasing contributions of HF-OC to bulk soil OC and the low Δ<sup>14</sup>C values of HF-OC. The stability of HF-OC was greater in subsoils than in topsoils; nevertheless, a portion of HF-OC was active throughout the profile. The decrease in Δ<sup>14</sup>C (increase in age) of HF-OC with soil depth was related to soil pH as well as to dissolved OC fluxes. This indicates that dissolved OC translocation contributes to the formation of subsoil HF-OC and shapes the Δ<sup>14</sup>C profiles. While quantitatively less important than OC in the HF, consistent older ages of oLF-OC than fLF-OC indicate that occlusion of LF-OC in aggregates also contributes to OC stability in subsoils. Overall, our results showed that association with minerals is the most important factor in stabilization of OC in soils.
In early 1992, a silvoarable experiment, comprising four poplar (Populus spp.) hybrids (at a spacing of 10 m x 6.4 m) and four arable treatments, was established at three contrasting lowland sites in England. By the end of 1998, seven years after planting, the height of the poplar hybrid Beaupré (11.9 m) was greater than those of the hybrids Gibecq, Robusta and Trichobel (8.9-9.8 m). The trees at the most exposed site had the shortest height (9.2 m) and the greatest diameter at breast height (173 mm). Tree growth was also affected by the arable treatments. The height (9.5 m) and diameter (143 mm) of the trees bordered on both sides by a continuous rotation of arable crops were 89% and 79%, respectively, of those bordered on both sides by a regularly cultivated fallow. This result could be explained by competition for water. Across the three sites, in the presence of the trees the yield per unit cropped area, relative to that in the control areas, was an average of 4% less in the first three years and an average of 10% less between years four and six. However the specific responses were dependent on the arable crop. The experiment also included an alternately-cropped arable treatment, where the crop was alternated with a one-year bare fallow. The benefits of a preceding fallow, rather than a cereal crop, for yield were greatest for wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) and least for field beans (Vicia faba L.),peas(Pisum sativum L.) and mustard (Brassica alba L.).
In response to the declining soil fertility in southern Africa and the negative effects that this leads to, such as food insecurity besides other developmental challenges, fertilizer tree systems (FTS) were developed as technological innovation to help smallholder farmers to build soil organic matter and fertility in a sustainable manner. In this paper, we trace the historical background and highlight the developmental phases and outcomes of the technology. The synthesis shows that FTS are inexpensive technologies that significantly raise crop yields, reduce food insecurity and enhance environmental services and resilience of agro-ecologies. Many of the achievements recorded with FTS can be traced to some key factors: the availability of a suite of technological options that are appropriate in a range of different household and ecological circumstances, partnership between multiple institutions and disciplines in the development of the technology, active encouragement of farmer innovations in the adaptation process and proactive engagement of several consortia of partner institutions to scale up the technology in farming communities. It is recommended that smallholder farmers would benefit if rural development planners emphasize the merits of different fertility replenishment approaches and taking advantage of the synergy between FTS and mineral fertilizers rather than focusing on 'organic vs. inorganic' debates.
Despite widespread use in the literature, there seems to be little consensus on what the term ‘carbon (C) sequestration’ means. We differentiate between endogenous C, which fluxes within a system, and exogenous C, which fluxes between systems. Here we define ‘endogenous C sequestration’ as occurring when C fixation to release ratio is greater than one (fixation(a,s)/release(a,s) >1), expressed at the briefest, annually (a) and budgeted within a specified system (s). We distinguish between sequestered C (stored for >1 year) and temporarily utilized biologic C (i.e., labile C present within a living organism), developing equations for herbaceous and woody plant systems. Standardized expression of C sequestration with incorporation of descriptors, for example ‘somatic C sequestration(10 year, forest)’, clarifies the location, timescale and system being considered and should allow for increased transparency and improved communication for climate change debates and C budgeting.
This book provides a synthesis of plant-soil-plant interactions from the plot to landscape scale. It focuses on the process level, which is relevant to many types of multispecies agroecosystems (agroforestry, intercropping and others). It also links basic research to practical application (and indigenous knowledge) in a wide range of systems with or without trees, and considers implications of below-ground interactions for the environment and global change issues. The contents include root architecture and dynamics, plant-soil biota interactions, soil biodiversity and food webs, water and nutrient cycling, and the necessary linkage to modelling approaches.
Climate change adaptation and mitigation are usually the objects of separate projects, but in this review we argue that in agricultural contexts, there are often technical and financial advantages in pursuing them simultaneously. This is because (1) adaptation planning is often necessary for mitigation (i.e., carbon sequestration) planning, especially for assessing future climate risks to mitigation investments, (2) certain land-use interventions can have both adaptation and mitigation benefits, and (3) carbon finance can help in supporting adaptation which still tends to be underfunded. Agroforestry and ecosystem conservation are key approaches in the integration of climate change adaptation and mitigation objectives, often generating significant co-benefits for local ecosystems and biodiversity. Synergies between climate change adaptation and mitigation actions are particularly likely in projects involving income diversification with tree and forest products, reduction of the susceptibility of land-use systems to extreme weather events, improvement of soil fertility, fire management, wind breaks, and the conservation and restoration of forest and riparian corridors, wetlands, and mangroves. On the other hand, trade-offs between adaptation and mitigation are possible when fast-growing tree monocultures for mitigation conflict with local tree and forest uses, making livelihoods more vulnerable, when trees are planted in water-scarce areas conflicting with local water uses, and in some cases when “climate-smart” agroforestry practices conflict with the need for agricultural intensification to produce increasing amounts of food for a growing population. Such conflicts need to be avoided through careful, site-specific, and participatory project development. We conclude that adaptation considerations should be included in mitigation project planning and integrated adaptation and mitigation activities should be prioritized in carbon markets and policy formation.
The perception that agroforestry systems have higher potential to sequester carbon than comparable single-species crop systems or pasture systems is based on solid scientific foundation. However, the estimates of carbon stock of agroforestry systems in Africa — reported to range from 1.0 to 18.0 Mg C ha−1 in aboveground biomass and up to 200 Mg C ha−1 in soils, and their C sequestration potential from 0.4 to 3.5 Mg C ha−1 yr−1–are based on generalizations and vague or faulty assumptions and therefore are of poor scientific value. Although agroforestry initiatives are promising pathways for climate-change mitigation, rigorous scientific procedures of carbon sequestration estimations are needed for realizing their full potential.
Depletion of ecosystem carbon stocks is a significant source of
atmospheric CO2 and reducing land-based emissions and
maintaining land carbon stocks contributes to climate change mitigation.
We summarize current understanding about human perturbation of the
global carbon cycle, examine three scientific issues and consider
implications for the interpretation of international climate change
policy decisions, concluding that considering carbon storage on land as
a means to 'offset' CO2 emissions from burning fossil fuels
(an idea with wide currency) is scientifically flawed. The capacity of
terrestrial ecosystems to store carbon is finite and the current
sequestration potential primarily reflects depletion due to past land
use. Avoiding emissions from land carbon stocks and refilling depleted
stocks reduces atmospheric CO2 concentration, but the maximum
amount of this reduction is equivalent to only a small fraction of
potential fossil fuel emissions.
Expansion of agricultural land use has increased emission of greenhouse gases, exacerbating climatic changes. Most agricultural soils have lost a large portion of their antecedent soil organic carbon storage, becoming a source of atmospheric carbon-dioxide. In addition, agricultural soils can also be a major source of nitrous oxide and methane. Adoption of conservation agricultural practices may mitigate some of the adverse impacts of landuse intensification. However, optimal implementation of these practices is not feasible under all physical and biotic conditions. Of a wide range of conservation practices, the most promising options include agroforestry systems and soil application of biochar, which can efficiently sequester large amounts of carbon over the long-run. In addition, these practices also increase agronomic productivity and support a range of ecosystem services. Payments to farmers and land managers for sequestrating carbon and improving ecosystem services is an important strategy for promoting the adoption of such practices, aimed at mitigating climate change while decreasing environmental footprint of agriculture and sustaining food security.
Agroforestry is one of the most conspicuous land use systems across landscapes and agroecological zones in Africa. With food shortages and increased threats of climate change, interest in agroforestry is gathering for its potential to address various on-farm adaptation needs, and fulfill many roles in AFOLU-related mitigation pathways. Agroforestry provides assets and income from carbon, wood energy, improved soil fertility and enhancement of local climate conditions; it provides ecosystem services and reduces human impacts on natural forests. Most of these benefits have direct benefits for local adaptation while contributing to global efforts to control atmospheric greenhouse gas concentrations. This paper presents recent findings on how agroforestry as a sustainable practice helps to achieve both mitigation and adaptation objectives while remaining relevant to the livelihoods of the poor smallholder farmers in Africa.
Silvopasture systems combine trees, forage, and livestock in a variety of different species and management regimes, depending on the biophysical, economic, cultural, and market factors in a region. We describe and compare actual farm practices and current research trials of silvopastoral systems in eight regions within seven countries of the world: Misiones and Corrientes provinces, Argentina; La Pampa province, Argentina; northwestern Minas Gerais, Brazil; the Aysén region of Patagonia, Chile; the North Island of New Zealand; the Southeast United States; Paraguay; and Uruguay. Some countries use native trees and existing forests; some use plantations, particularly of exotic species. Natural forest silvopasture systems generally add livestock in extensive systems, to capture the benefits of shade, forage, and income diversification without much added inputs. Plantation forest systems are more purposive and intensive, with more focus on joint production and profits, for small owners, large ranches, and timber companies. Trends suggest that more active management of both natural and planted silvopastoral systems will be required to enhance joint production of timber and livestock, achieve income diversification and reduce financial risk, make more profit, improve environmental benefits, and realize more resilience to adapt to climate change.
Ever since the Kyoto Protocol, agroforestry has gained increased attention as a strategy to sequester carbon (C) and mitigate global climate change. Agroforestry has been recognized as having the greatest potential for C sequestration of all the land uses analyzed in the Land-Use, Land-Use Change and Forestry report of the IPCC; however, our understanding of C sequestration in specific agroforestry practices from around the world is rudimentary at best. Similarly, while agroforestry is well recognized as a land use practice capable of producing biomass for biopower and biofuels, very little information is available on this topic. This thematic issue is an attempt to bring together a collection of articles on C sequestration and biomass for energy, two topics that are inextricably interlinked and of great importance to the agroforestry community the world over. These papers not only address the aboveground C sequestration, but also the belowground C and the role of decomposition and nutrient cycling in determining the size of soil C pool using specific case studies. In addition to providing allometric methods for quantifying biomass production, the biological and economic realities of producing biomass in agroforestry practices are also discussed.
Afforestation is known as an available mitigation activity to climate change because it causes sequestration of CO2 from the atmosphere and stores it as the living biomass and the dead organic matter. However, the response of soil organic carbon (SOC) to afforestation in deep soil layers is still poorly understood. We surveyed previously published literature for changes in deep SOC (defined as at least 10 cm deeper than the 0–10 cm layer) after afforestation of croplands and grasslands (total 63 sites from 56 literature), in order to examine changes in deep SOC and quantify the relationship between SOC change rates in topsoil and subsoil. The results of the meta analysis indicated that the responses of SOC to afforestation were opposite for cropland than grassland. The SOC in soil depth layers of 0–10, 10–20, 20–40, 40–60 and 60–80 cm were reduced with afforestation of grassland but not significantly (p > 0.05), while conversion of cropland to forests (trees or shrubs) increased SOC significantly for each soil depth layer up to 60 cm depth (p < 0.05). Significant relationships of SOC change rate were found between topsoil (0–20 cm) and deeper soil layers (20–40 and 40–60 cm). The linear regression showed that SOC change rate in 0–40 cm, 0–60 cm, and 0–100 cm soil profiles was 1.33, 1.49, and 1.55 times greater, respectively than the change rates in the corresponding 0–20 cm depth profile. Partial correlation analysis revealed that stand age and initial SOC content were determinants of deep soil SOC change after afforestation of agricultural soils. This study also showed that the O horizon can play an important role in carbon sequestration after afforestation of agricultural sites. We concluded that subsoil carbon must be taken into account when evaluating of SOC change with afforestation and, therefore, recommended that the soil sampling depth for afforested soils be set to at least 60 cm in mineral soils and include the O horizon. However, due to poor study designs and lack of standardized sampling protocols in the literature, these results were high in uncertainty.
The latest carbon dioxide emissions continue to track the high end of
emission scenarios, making it even less likely global warming will stay
below 2 °C. A shift to a 2 °C pathway requires immediate
significant and sustained global mitigation, with a probable reliance on
net negative emissions in the longer term.
A considerable amount of data is available about above-ground biomass production and turnover in tropical agroforestry systems, but quantitative information concerning root turnover is lacking. Above- and below-ground biomass dynamics were studied during one year in an alley cropping system withGliricidia sepium and a sole cropping system, on aPlinthic Lixisol in the semi-deciduous rainforest zone of the Côte d'Ivoire. Field crops were maize and groundnut. Live root mass was higher in agroforestry than in sole cropping during most of the study period. This was partly due to increased crop and weed root development and partly to the presence of the hedgerow roots. Fine root production was higher in the alleys and lower under the hedgerows compared to the sole cropping plots. Considering the whole plot area, root production in agroforestry and sole cropping systems was approximatly similar with 1000–1100 kg ha–1 (dry matter with 45% C) in 0–50 cm depth; about 55% of this root production occured in the top 10 cm. Potential sources of error of the calculation method are discussed on the basis of the compartment flow model. Above-ground biomass production was 11.1 Mg ha–1 in sole cropping and 13.6 Mg ha–1 in alley cropping, of which 4.3 Mg ha–1 were hedgerow prunings. The input of hedgerow root biomass into the soil was limited by the low root mass ofGliricidia as compared to other tree species, and by the decrease of live root mass of hedgerows and associated perennial weeds during the cropping season, presumably as a result of frequent shoot pruning.
Conceptual models suggest that stability and age of organic carbon (OC)
in soil depends on the source of plant litter, occlusion within
aggregates, incorporation in organo-mineral complexes, and location
within the soil profile. Various tools like density fractionation,
mineralization experiments, and radiocarbon analyses have been used to
study the importance of these mechanisms. We systematically apply them
to a range of European soils to test whether general controls emerge
even for soils that vary in vegetation, soil types, parent material, and
land use. At each of the 12 study sites, 10 soil cores were sampled in
10 cm depth intervals to 60 cm depth and subjected to density
separation. Bulk soil samples and density fractions (free light
fractions - fLF, occluded light fractions - oLF, heavy fractions - HF)
were analysed for OC, total nitrogen (TN), δ13C, and
Δ14C. Bulk samples were also incubated to determine
mineralizable OC. Declining OC-normalized CO2
release and increasing age with soil depth confirm greater stability of
OC in subsoils across sites. Depth profiles of LF-OC matched those of
roots, which in turn reflect plant functional types in soil profiles not
subject to ploughing. Modern Δ14C signatures and
positive correlation between mineralizable C and fLF-OC indicate the fLF
is an easily available energy and nutrient source for subsurface
microbes. Fossil C derived from the geogenic parent material affected
the age of OC especially in the LF at three study sites. The overall
importance of OC stabilization by binding to minerals was demonstrated
by declining OC-normalized CO2 release rates with increasing
contributions of HF-OC to bulk soil OC and the low Δ14C
values of HF-OC. The stability of HF-OC was greater in subsoils than in
topsoils; nevertheless, a portion of HF-OC was active throughout the
profile. The decrease in Δ14C (increase in age) of
HF-OC with soil depth was related to soil pH as well as to dissolved OC
fluxes. This indicates that dissolved OC translocation contributes to
the formation of subsoil HF-OC and shapes the Δ14C
profiles. While quantitatively less important than OC in the HF,
consistent older ages of oLF-OC than fLF-OC indicate that occlusion of
LF-OC in aggregates also contributes to OC stability in subsoils.
Overall, our results showed that association with minerals is the most
important factor in stabilization of OC in soils.
Dissolved organic matter (DOM) is defined as the organic matter fraction in solution that passes through a 0.45 μm filter. Although DOM is ubiquitous in terrestrial and aquatic ecosystems, it represents only a small proportion of the total organic matter in soil. However, DOM, being the most mobile and actively cycling organic matter fraction, influences a spectrum of biogeochemical processes in the aquatic and terrestrial environments. Biological fixation of atmospheric CO2 during photosynthesis by higher plants is the primary driver of global carbon cycle. A major portion of the carbon in organic matter in the aquatic environment is derived from the transport of carbon produced in the terrestrial environment. However, much of the terrestrially produced DOM is consumed by microbes, photo degraded, or adsorbed in soils and sediments as it passes to the ocean. The majority of DOM in terrestrial and aquatic environments is ultimately returned to atmosphere as CO2 through microbial respiration, thereby renewing the atmospheric CO2 reserve for photosynthesis. Dissolved organic matter plays a significant role in influencing the dynamics and interactions of nutrients and contaminants in soils and microbial functions, thereby serving as a sensitive indicator of shifts in ecological processes. This chapter aims to highlight knowledge on the production of DOM in soils under different management regimes, identify its sources and sinks, and integrate its dynamics with various soil processes. Understanding the significance of DOM in soil processes can enhance development of strategies to mitigate DOM-induced environmental impacts. This review encourages greater interactions between terrestrial and aquatic biogeochemists and ecologists, which is essential for unraveling the fundamental biogeochemical processes involved in the synthesis of DOM in terrestrial ecosystem, its subsequent transport to aquatic ecosystem, and its role in environmental sustainability, buffering of nutrients and pollutants (metal(loid)s and organics), and the net effect on the global carbon cycle.
Soil disturbance from tillage is a major cause of organic matter depletion and reduction in the number and stability of soil aggregates when native ecosystems are converted to agriculture. No-till (NT) cropping systems usually exhibit increased aggregation and soil organic matter relative to conventional tillage (CT). However, the extent of soil organic matter changes in response to NT management varies between soils and the mechanisms of organic matter stabilization in NT systems are unclear. We evaluated a conceptual model which links the turnover of aggregates to soil organic matter dynamics in NT and CT systems; we argue that the rate of macroaggregate formation and degradation (i.e. aggregate turnover) is reduced under NT compared to CT and leads to a formation of stable microaggregates in which carbon is stabilized and sequestered in the long term. Therefore, the link between macroaggregate turnover, microaggregate formation, and C stabilization within microaggregates partly determines the observed soil organic matter increases under NT. q 2000 Elsevier Science Ltd. All rights reserved.
This book provides a synthesis of plant-soil-plant interactions from the plot to landscape scale. It focuses on the process level, which is relevant to many types of multispecies agroecosystems (agroforestry, intercropping and others). It also links basic research to practical application (and indigenous knowledge) in a wide range of systems with or without trees, and considers implications of below-ground interactions for the environment and global change issues. The contents include root architecture and dynamics, plant-soil biota interactions, soil biodiversity and food webs, water and nutrient cycling, and the necessary linkage to modelling approaches.
Agroforestry refers to land use systems in which trees or shrubs are grown in association with agricultural crops, or pastures and livestock. From its inception, it has contained a strong element of soil management. Well-designed and managed agroforestry systems have the potential to control runoff and erosion, maintain soil organic matter and physical properties and promote nutrient cycling. By these means agroforestry can make a suitable contribution to sustainable land use. This new edition summarises the present state of knowledge and research of agronomy systems: the plant-soil processes; soil conservation and erosion control; soil management and nutrient cycling. It is essential reading for all concerned with agroforestry whether as students, research scientists or for practical purposes of development.