Full-text (1)
Content uploaded by Emilio J. Gonzalez-Sanchez
Author content
All content in this area was uploaded by Emilio J. Gonzalez-Sanchez on Oct 09, 2018
Content may be subject to copyright.
A preview of the PDF is not available
Technical Report
PDF Available
Making Climate Change Mitigation and Adaptability Real in Africa with Conservation Agriculture
Abstract
In this report, the authors have gathered essential information on how the agricultural sector can respond to climate change through Conservation Agriculture (CA). This document aims to serve as a basis for decision-making based on science and agricultural experimentation in Africa.
... Hunger is a major hindrance to livelihoods improvement (Ashley & Carney, 1999). By achieving SDG2, food production would increase, resilience to extreme weather conditions such as drought would be strengthened and soil quality improved (Gonzalez-Sanchez et al., 2018;Rosegrant, Koo et al., 2014). ...
Across Sub-Saharan Africa, agricultural practices for sustainable intensification need to be up-scaled from project interventions to institutional mainstreaming. However, several constraints, including a general lack of resources and knowledge, limited institutional support and challenging market conditions hamper this process. The objective of this study was to develop region-specific options to promote Conservation Agriculture (CA) in the Laikipia region, Kenya. We applied the Transformative Learning Approach (TLA) to stimulate and nurture a joint learning process around CA, to diagnose hindering and supporting factors for up-scaling of CA and to develop options for change promotion. Through a series of field visits, we collected and analyzed data using elements of the TLA approach: i.e. agro-ecosystem health check, stakeholder mapping, participatory videos and the Qualitative Assessment tool for CA adoption (QAToCA). Our findings reveal that up-scaling of CA is hindered by inefficient agricultural market structures, limited access to CA specific biological (residue, seeds), and technical inputs (e.g. machinery), a lack of finances, and absence of knowledge. We recommend four options for further CA promotion in the region: localised expertise (e.g. crop-livestock integration), unbiased facilitation (e.g. careful choice of multipliers), subsidized inputs (e.g. micro-credits) and robust institutional system support (e.g. stable agricultural policies).
... Second, a mixture of tree species can exploit the nutrient and soil moisture pool of soil profiles more diversely than a mono-species tree stand can [33], thus minimizing the risk of nutrient and water depletion (Figure 1). Therefore, the increase in soil biodiversity leads to a better responsiveness to extreme phenomena resulting from climate change that can worsen their degradation, thus improving the resilience of the ecosystem [74] and contributing to a lower risk of landslides, droughts, or soil erosion. Figure 8. Relationship between ecosystem services, soil organic carbon, and soil functions in a scenario consisting of extracting timber and replacing with trees of different species (i.e., increase tree species diversity). ...
In 1955, after the Korean War, only 35% of the national land area in South Korea was covered by forests. In the 1960s, the Korean Government implemented the national forestation program in order to increase the extent of the forest surface and thereby counteract the negative ecological consequences from deforestation, such as erosion and ground instability. According to previous studies, this led to an increase in carbon (C) accumulated in the forest biomass of 1.48 Gt CO2 (0.40 Gt C) in the period 1954-2012. However, these studies did not take into account the amount of soil organic carbon (SOC) that was accumulated during that period and the influence of management practices on soil ecosystem services. Currently, South Korean authorities are considering the idea of implementing some forest management practices in order to increase timber extraction (e.g., by reducing the cutting age of the trees or by applying thinning and tending measures). In this study, we assess the influence of these management regimes on SOC dynamics and propose a theoretical framework to assess the influence of forest management practices on three ecosystem services, namely, C sequestration, water supply, and biomass production, while considering soil functioning, and especially SOC, as a group of supporting services underpinning the three named ecosystem services. We find that, in terms of SOC sequestration, reducing the cutting age from 80 to 40 years would be suitable only in the case of high biomass production forests, whereas in the case of lower biomass production forests reducing the cutting age would achieve very low SOC levels. However, we propose that increasing tree species diversity, even though it would not lead to a direct increase in the SOC content, could help to lessen the negative effects of reducing the cutting age by improving other soil properties, which in turn positively affect soil functioning (e.g., soil biodiversity, nutrient availability) and the resilience of the forest ecosystem. Finally, we discuss potential policy approaches to incentivize sustainable management practices in South Korean forests from a soil protection perspective.
The intensification of tillage agriculture has been aimed to increase crop yields. However, this has also been causing degradation of agricultural lands and natural resources. In this regard, Conservation Agriculture (CA) is an alternate paradigm, which integrate the conservation into agriculture and make that regenerative, conserving and resilient than the conventional tillage agriculture. CA is, thus, an ecosystem approach to improve and sustain productivity, and increase profits and resource base. In this chapter, some aspects of conservation that are integrated into agriculture when practicing CA are described. The potential of CA in improving productivity, economic, social and environmental benefits to farmers and the society at large have been discussed.
World soils contain about 1500 gigatons of organic carbon. This large carbon reserve can increase atmospheric concentrations of CO2 by soil misuse or mismanagement, or it can reverse the ‘greenhouse’ effect by judicious land use and proper soil management. Soil Processes and the Carbon Cycle describes soil processes and their effects on the global carbon cycle while relating soil properties to soil quality and potential and actual carbon reserves in the soil. In addition, this book deals with modeling the carbon cycle in soil, and with methods of soil carbon determinations.
The African continent is one of the most vulnerable regions to future climate change. Research now demonstrates that constraining anthropogenic warming to 1.5 °C instead of 2 °C will significantly lower the risk of heatwaves to inhabitants.
The 4‰ initiative launched by the French government at COP21 in Paris in December 2015 aspires to increase global soil organic carbon (SOC) stocks at a rate of 0.4% per year. We conducted a systematic literature review on SOC storage under agroforestry and conservation agriculture systems in sub-Saharan Africa, where we reported 66 and 33 cases for both systems respectively. The results showed that SOC storage rates were significantly higher than 4‰ yr−1 in fallows and in multistrata agroforestry systems (P = 0.0001 and 0.0178, respectively), but not in alley cropping and parklands systems. For conservation agriculture, SOC storage rates were only significantly higher than 4‰ yr−1 (P = 0.0438) when all three principles were applied, i.e. no- or minimum tillage combined with crop residue retention and intercropping or rotation. The data showed very large variability in SOC storage rates as the result of various factors, including previous land-use history, experimental set up and approach used to determine SOC storage (diachronic versus synchronic approach), soil type, depth of soil sampling, type of crops and management, and duration of the experiment. SOC storage rates significantly decreased with time in the agroforestry systems (P = 0.0328). However, we were unable to find significant relationships with initial SOC stocks or tree density. Given the limited published data and the high variability in results, no significant relationships between SOC storage rates and site variables were found for conservation agriculture. We argue that there is a potential for SOC storage in agricultural soils of sub-Saharan Africa, as illustrated by SOC gaps observed on smallholder farms. Low SOC levels are, however, to a great extent the result of limited resources of most smallholder farmers. Practices such as agroforestry and conservation agriculture can restore SOC in these soils, but the 4‰ initiative has to be implemented on the grounds of the positive impact on crop productivity rather than on climate change mitigation. The efficiency in doing so will depend on the specific situations and will need economic support to smallholder farmers, including the promotion of good markets for sale of extra produce and for input supply, effective private support and policy, such as credit schemes and subsidies for inputs, and efficient extension services which incentivize farmers to invest in new technologies.
If the United Nations Sustainable Development Goals are to be achieved, African smallholder farmers will need to embrace new technologies such as conservation agriculture (CA) in order to increase both their productivity and sustainability. Yet farmers have been slow to embrace CA and when they have, they are inclined to do so at limited intensities. Current investigations tend to apply binary frameworks that classify all utilizations as ‘adoption’, and do not consider in depth the farmer perspectives and contextual realities that affect farmer decision-making on the intensity of use. We analyze 57 in-depth, semi-structured interviews with farmers who implement CA to understand why they tend to do so at limited intensities and what is required to intensify their CA activities, both for them and others within their communities. While most farmers reported substantial yield benefits from using CA, this was mainly related to input intensification (particularly herbicides) and was limited by constrained financial resources. Overall, the intensity of CA utilization was constrained due to farmer-identified constraints across their physical, financial, human and informational resources. Because of this, stagnation at low intensities of CA utilization was common, reflecting the assumed transformational adoption pathway for CA and the focus on binary adoption, as opposed to modification and the broader utilization process. To overcome this, we propose a more nuanced transitional approach focused on the intensification of four broader principles of CA over time [i.e., (1) strategic tillage, (2) soil protection, (3) crop diversification and (4) input management] as opposed to the strict packaging of CA practices. Such a change in approach will foster increased positive perceptions within the community and allow farmers to locally adapt CA to build their own way toward complete CA utilization and with less need for subsidization.
The supply side of the food security engine is the way we farm. The current engine of conventional tillage farming is faltering and needs to be replaced. It is faltering because it causes unacceptable level of soil erosion and land degradation, and loss in yield potential, productivity, efficiency, resilience and ecosystem services. ‘Business as usual’ is no longer considered to be a suitable option for the future. This article addresses the supply side issues of agriculture to meet future agricultural demands for food and by industry with the alternate Conservation Agriculture (CA) paradigm (involving no-till seeding and weeding in soils with mulch cover and in diversified cropping) that is able to raise productivity sustainably and efficiently, reduce costly inputs, regenerate degraded land, minimize soil erosion, and harness the flow of ecosystem services. CA is an ecosystems approach to farming capable of enhancing not only the economic and environmental performance of crop production and land management, but also promotes a mindset change for producing ‘more from less’, the key attitude towards sustainable production intensification. CA is spreading globally in all continents at an annual rate of some 10 million hectares of cropland. In 2013–2014, CA covered more than 157 million hectares of rainfed and irrigated cropland and it is likely that its current spread is close to some 200 million hectares. In addition, perennial cropping systems such as orchards and plantations are being transformed into CA systems in all continents. In addition to being a best option for large-scale farmers, CA offers a real pro-poor agricultural development model to support sustainable agricultural intensification for low input smallholder farmers.
Abstract Throughout the Sahel, food insecurity remains a persistent threat. A few studies have shown that Piliostigma reticulatum, a dominant native shrub in parklands from Senegal to Sudan, can positively impact crop yields. However, there are no experiments that measure whether this species can stabilize long-term crop productivity under erratic rainfall. Therefore, an 11-year study of an optimized P. reticulatum intercropping system (1000 shrubs ha−1 with annual coppiced residue soil amendments) was initiated in 2004 in Senegal, West Africa to determine its impacts on crop productivity and soil quality. The experiment was a split-plot factorial design with the main plot shrubs (with and without) and the subplot fertilizer rate (0, 0.5, 1, and 1.5 times the recommended N-P-K rate) with an annual groundnut (Arachis hypogaea) and pearl millet (Pennisetum glaucum) crop rotation. Yield, biomass, soil carbon, and soil and plant nutrient data from 2011 to 2015 were compared with data from 2004 to 2007. The presence of shrubs increased millet and groundnut yield from 2011 to 2015 and rainfall water use efficiency (WUE) between 2004 and 2015. Without fertilizer addition, the shrub plots had approximately 2 times greater millet yield throughout the duration of this experiment. The presence of shrubs also improved soil quality, as evidenced by significantly greater C in the fraction <53 μm and total C in shrub over non-shrub plots. Thus, P. reticulatum intercropping promotes C sequestration. In addition, five macronutrients (N, K, Ca, Mg, S) and two micronutrients (Mn and Cu) were significantly greater in the shrub plots. The results provide strong evidence that intercropping with P. reticulatum is an ecological agroforestry system for the Sahel that can remediate soils, increase crop yields, and buffer climate change.
