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Assessing the Environmental Benefits of Compost Use-on-Land through an LCA Perspective

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Abstract

Due to increasing compost use in agriculture, there is an urgent need to evaluate compost benefits and impacts versus other fertilizers. Here we review the recent progress made in the quantification of positive effects associated with compost use on land using life cycle assessment (LCA), an internationally recognised environmental tool. Nine environmental benefits were identified in an extensive literature review: nutrient supply, carbon sequestration, weed pest and disease suppression, increase in crop yield, decreased soil erosion, retention of soil moisture, increased soil workability, enhanced soil biological properties and biodiversity, and gain in crop nutritional quality. Quantitative figures for each benefit were drawn from the literature and classified into short-term: less than 1 year; mid-term: less than 10 years and long-term: less than 100 years.

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... Among organic fertilizers, compost has receiving great attention lately. The most evident advantages of its application in agriculture are I) the reduction in N fertilization by synthetic products, II) its role as a carbon sink, and III) the improvement in water retention capacity of soils [41][42][43]. The use of compost is currently recognized as a sustainable practice in itself because the frequently used materials derive from the recovery of selected organic matrices, whose disposal would be particularly complex and expensive [44]. ...
... The compost from organic fraction municipal solid waste (OFMSW), properly treated in accordance with laws, shows an interesting improvement in plants' performance, particularly when combined with mineral fertilization. Application of OFMSW compost, alone or in combination with mineral N fertilizers, was tested in several crops with contrasting results [41][42][43]46]. On one hand, several studies showed a positive effect of OFMSW on yield and quality response mainly attributable to the best plant's nutrients uptake (N, P, K and Ca) under compost application [42,[46][47][48][49]. On the other hand, others reported some negative effects [42,50]. ...
Article
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A biennial experiment (2009 and 2010) was conducted at Calvi (Benevento, Southern It-aly) to evaluate the effect of compost by organic fraction municipal solid waste (OFMSW), in combination with mineral nitrogen (N) fertilization, on yield and quality of three Dark Fire-cured (Kentucky) tobacco cultivars commonly cultivated at Benevento province (Campania region, Southern Italy). Six N fertilization treatments (N0 = soil N reserves available for plant growth; MIN = 135 kg ha −1 of N applied as mineral fertilizer; C10 = 10 Mg d.w. ha −1 compost; C10N = 10 Mg d.w. ha −1 compost + 50% MIN; C20 = 20 Mg d.w. ha −1 compost; C20N = 20 Mg d.w. ha −1 compost + 50% MIN) were combined with the following cultivars: i) Foiano, medium early maturing; ii) Riccio Beneventano (local ecotype), medium maturing; iii) SKL, medium maturing. Yield of cured leaves (Mg ha −1) and growth components (number of leaves per plant, mean individual leaf area, leaf area per plant, specific leaf weight, stem diameter and height) and color parameters (L*, a*/b*) were measured. Leaf quality traits (nitrates, total N and alkaloids contents, score) and N use efficiency were also determined. The best growth and yield performance was reached in 2010 when plants were taller, developed both stems that were more robust and leaves having greater individual leaf area, and showed a higher leaf area per plant than in the first year. Regardless of the form of applied N (compost, mineral fertilizer, or a combination of both), tobacco plants appeared to be directly and positively influenced by increasing quota of readily available N received by each treatment , which was determined at the beginning of field growth by N soil balance and taking into account the percentage of N supplied by organic (compost) and mineral fertilizers. Results obtained with compost treatments, particularly when combined with mineral fertilizer (at C10N more than C20N), appeared comparable or sometimes better than those of full mineral fertilization although N fertilization by synthetic products was applied at very low doses.
... The positive responses of soil WHC after a combined application of biochar with either compost [68] or vermicompost [69] were also found in previous research. Application of OM to soils is expected to improve soil moisture content, micro-and macro-pore density, and thus infiltration [70][71][72]. Despite its initial very low WHC and general poor characteristics (Table 1), the Ferralsol generally did not benefit from these OM applications. ...
... Despite its initial very low WHC and general poor characteristics (Table 1), the Ferralsol generally did not benefit from these OM applications. This contradicts several studies where biochar [73][74][75] or compost [69][70][71][72] increased water storage in soils, particularly also for sandy soils with low initial WHC common in tropical regions [38,73,74] and also for other Ferralsols [68]. In addition, we observed the strongest negative responses in soil WHC in the presence of rice husk biochar, which contradicts a study using the same biochar feedstock [75]. ...
Article
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Organic matter management is key to sustain ecosystem services provided by soils. However, it is rarely considered in a holistic view, considering local resources, agro-environmental effects and harmonization with farmers’ needs. Organic inputs, like compost and biochar, could represent a sustainable solution to massive current challenges associated to the intensification of agriculture, in particular for tropical regions. Here we assess the potential of agricultural residues as a resource for farmer communities in southwestern India to reduce their dependency on external inputs and sustain ecosystem services. We propose a novel joint evaluation of farmers’ aspirations together with agro-environmental effects of organic inputs on soils. Our soil quality evaluation showed that biochar alone or with compost did not improve unilaterally soils in the tropics (Anthroposol, Ferralsol and Vertisol). Many organic inputs led to an initial decrease in water-holding capacities of control soils (-27.3%: coconut shell biochar with compost on Anthroposol). Responses to organic matter inputs for carbon were strongest for Ferralsols (+33.4% with rice husk biochar), and mostly positive for Anthroposols and Vertisols (+12.5% to +13.8% respectively). Soil pH responses were surprisingly negative for Ferralsols and only positive if biochar was applied alone (between -5.6% to +1.9%). For Anthroposols and Vertisols, highest increases were achieved with rice husk biochar + vermicomposts (+7.2% and +5.2% respectively). Our socio-economic evaluation showed that farmers with a stronger economical position showed greater interest towards technology like biochar (factor 1.3 to 1.6 higher for farmers cultivating Anthroposols and/or Vertisols compared to Ferralsols), while poorer farmers more skepticism, which may lead to an increased economical gap within rural communities if technologies are not implemented with long-term guidance. These results advocate for an interdisciplinary evaluation of agricultural technology prior to its implementation as a development tool in the field.
... The finish product of composting is widely recognized as an organic fertilizer or soil amendment. A comparable amount of studies has suggested that compost is a great long-term source of nitrogen, organic matter, and many essential trace minerals [4], [5]. A study of compost application over a three-year course showed a significant increase in total concentration and bioavailability of Cd and Zn [6]. ...
... A study of compost application over a three-year course showed a significant increase in total concentration and bioavailability of Cd and Zn [6]. Improvement on aggregate stability, porosity, and soil water holding capacity was also observed [5]. More specifically, sandy soils with low productivity could be improved by compost to sustain crop production [7]. ...
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Treatment of food waste has attracted widespread social attention. Home composting has been proved repeatedly to be a feasible practice to divert food waste from landfills and produce useful finished compost. The objective of this experiment is to find ways to improve the efficiency of such beneficial practice based on a school cafeteria setting and practical small-scale composting. Three additives, including activated carbon, biochar and wood ash are studied, and the efficiency and effectiveness of these three high carbon materials on small-scale synthetic food waste are compared by analyzation of 30-days sample reports and comparison of pile temperature during the whole process. Experimental results showed that all three additives improved composting efficiency, though their effects varied. The addition of wood ash resulted in the most organic matter, total carbon and total nitrogen among all four trials (including one control group without additive). Small scale synthetic food waste composting is indicated to be a practical and feasible approach. And with the help of wood ash addition, a more efficient mesophilic period is achieved.
... water retention and soil biodiversity among others) (Ondrasek et al., 2019). Organic amendments such as compost or manure are extensively being used as direct input of organic matter and other nutrients like N, P, K to the soil (Donn et al., 2014;Six et al., 2002), to improve soil structure and increase water holding capacity which has a special impact on the efficiency of water use in rainfed conditions (Ciadamidaro et al., 2016;Keener et al., 2018;Martínez-Blanco et al., 2013). Moreover, compost application leads to climate change benefits through organic waste recovery and consequently off-site reduction of greenhouse emissions, nutrient recycling and C sequestration (Lazcano et al., 2021;Ryals et al., 2015). ...
Article
Agro-industrial composts represent both a sustainable alternative to inorganic fertilizers and a waste recycling management tool. Albeit, there is still a great deal of uncertainty as to what extent their use can contribute to the global N2O budget. Here, two different composts [olive waste “alperujo” (AC) and biosolid (BC)] were tested during a three-year period to evaluate changes in N pools (NH4⁺ and NO3⁻), N2O emissions and key N-cycle associated genes [ammonia monooxygenase (amoA) and N2O reductase (nosZ)] in comparison with a control, treated only with mineral fertilization. To that end, a low dose (equivalent to 17.8 kg per tree of AC or BC) and high dose (equivalent to 26.7 kg per tree of AC+ or BC+) was applied to each individual plot composed of nine olive trees without irrigation in a completely randomized design. N2O emissions rates showed a high spatial and temporal variability and no significant changes were detected in N pools when comparing with the control. However, the fact that the soil treated with BC+ presented 20% more NO3⁻ compared to the control after the second compost addition and that the low doses of both composts displayed about 30% less NH4⁺ than the control, suggests different pathways in N mineralization. Moreover, the N balance showed that soils treated with AC used all N provided and in turn promoted native N consumption while soil amended with BC only consumed part of the exogenous N provided. The assessment of the bacterial amoA and nosZ genes reflected that it was tillage practices rather than fertilization which had the most significant impact on their abundance, decreasing this effect towards the end of the experiment. Our results showed that under Mediterranean conditions the use of agro-industrial byproducts do not contribute to N2O emissions and therefore it could be potentially used as a replacement of inorganic fertilizers favouring a circular economy of zero waste.
... Their catalysts empower them to degrade intense flotsam and jetsam. The genera Micrococcus, Bacillus, Streptomyces, Actinomyces, Azotobacter, Aspergillus, Penicillium and Trichoderma have also been examined by Ryckeboer et al., (2003);Velarde et al., (2004) and Martínez (2013) in various composts. ...
Article
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Treating trash fish and processing waste is one of the more conservative and naturally safe techniques for reusing waste created by the purchaser society. Because of the intricacy of substrates and middle of the road items, microbial decent variety and the progression of populaces is an essential to guarantee total biodegradation. In the present work, we examined the progression of microbial population amid fertilizing the soil procedure of natural division of marine junk fish and handling waste and some physical and synthetic parameters were pursued. Amid the procedure, the moisture content was kept up at 50-60% and the temperature was checked every day. The outcomes demonstrated that the substrate was colonized in significant extent by bacteria (45.5%), actinomycetes (31.8 %) and in lower number by fungi (22.7%), predominantly spoken to by Streptomyces, Pseudomonas, Bacillus and Actinomyces.
... The MSWC have shown comparable physio-chemical characteristics to other composts derived from different agro-industrial by-products ( Jodar et al., 2017). Application of MSWC is known to improve soil C storage ( Peltre et al., 2017), availability of water and nutrient to the crops grown ( Martínez-Blanco et al., 2013 and references therein), microbial biomass carbon, dehydrogenase activity values ( Fernandez et al., 2007), and plant growth and fruit production characteristics (Leogrande, et al., 2016). However, regardless of the attempts that have already been made to popularize the application of MSWC to agricultural lands in Sri Lanka, it is still in a subordinate level compared with the application of chemical fertilizers and other agricultural-based waste composts (AWC). ...
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Application of compost is known to improve the hydraulic characteristics of soils. The objective of this study was to examine the seasonal and short-term effects of solid waste compost amendments on selected hydrophysical properties of soil during dry and rainy seasons and to explore any negative impacts of municipal solid waste compost (MSWC) amendments on soil hydrophysical environment concerning Agriculture in low-country wet zone, Sri Lanka. Eight (T1–T8) MSWC and two (T9, T10) agricultural-based waste compost (AWC) samples were separately applied in the field in triplicates at 10 and 20 Mg ha ⁻¹ rates, with a control (T0). Field measurements (initial infiltration rate, Ii ; steady state infiltration rate, ISS ; unsaturated hydraulic conductivity, k ; sorptivity, SW ) were conducted and samples were collected (0–15 cm depth) for laboratory experiments (water entry value, hwe ; potential water repellency: measured with water drop penetration time, WDPT) before starting (Measurement I) and in the middle of (Measurement II) the seasonal rainfall (respectively 5 and 10 weeks after the application of compost). The difference in the soil organic matter (SOM) content was not significant between the dry and rainy periods. All the soils were almost non-repellent (WDPT = <1–5 s). The hwe of all the samples were negative. In the Measurement I, the Ii of the T0 was about 40 cm h ⁻¹ , while most treatments show comparatively lower values. The ISS , SW , and k of compost amended samples were either statistically similar, or showed significantly lower values compared with T0. It was clear that all the surface hydraulic properties examined in situ ( Ii , ISS , SW ) were higher in the Measurement I (before rainfall) than those observed in the Measurement II (after rainfall). Water potential differences in soils might have affected the surface hydrological properties such as SW . However, water potential differences would not be the reason for weakened ISS and k in the Measurement II. Disruption of aggregates, and other subsequent processes that would take place on the soil surface as well as in the soil matrix, such as particle rearrangements, clogging of pores, might be the reason for the weakened ISS and k in the Measurement II. Considering the overall results of the present study, compost amendments seemed not to improve or accelerate but tend to suppress hydraulic properties of soil. No significant difference was observed between MSWC and AWC considering their effects on soil hydraulic properties. Application of composts can be considered helpful to slower the rapid leaching by decreasing the water movements into and within the soil.
... However, the beneficial impacts can be variable and depend on soil conditions, the climate and weather, application rate, and are cropspecific. Compost application could also displace herbicides and pesticides, but due to the case-specific nature of compost application and herbicide and pesticide application, it was not included in this study (Heimersson et al., 2017;Martínez-Blanco et al., 2013b). Further investigation and improved models are required before the full benefits of compost can be quantified and included in an LCA context. ...
Article
In response to significant organic waste generation, environmental policies are increasingly mandating diversion of organic waste from landfills and promoting alternative management practices to produce energy and reduce greenhouse gas emissions (GHG). Anaerobic digestion and composting are organic waste treatment alternatives, however, both practices require careful management to prevent similar environmental impacts as landfills. A model was developed to assess the impact of anaerobic digestion followed by composting of food waste and green waste mixtures on net energy production, global warming potential and scarce water use. The model included the ability to vary the initial organic waste composition, decomposition kinetics and treatment time. Energy needs for composting aeration and water pumping, and water use decreased as anaerobic digestion time increased. Composting water use savings for an organic waste anaerobically digested for 90 days prior to composting compared to zero days prior to composting ranged between 25%–53% for different organic waste compositions (from 1:0 to 0:1 green waste to food waste ratios), and energy use savings for composting aeration and water pumping ranged between 15%–17% and 24%–54%, respectively, for the same conditions. For an anaerobic digestion pretreatment time of 30 days prior to composting, the analysis predicted scarce water use to be 0.31–1.09 m³ swe/Mg waste, primary energy use to be −168.5–298.3 MJ/Mg waste, and global warming potential to be 8.1–26.4 kg CO2e/Mg waste. The results will help inform the design and maintenance of waste treatment in resource-limited environments.
... Based on Chowdhury et al. (2014), 19% of the nitrogen in the manure after storage is estimated to be available for crops as NH 4 + . Moreover, it is assumed that 14% of the organic nitrogen in the manure is mineralized during the first year (Martínez-Blanco et al., 2013). ...
Article
Anaerobic digestion of cow dung with new feedstock such as crop residues to increase the biogas potential is an option to help overcoming several issues faced by India. Anaerobic digestion provides biogas that can replace biomass cooking fuels and reduce indoor air pollution. It also provides digestate, a fertilizer that can contribute to compensate nutrient shortage on agricultural land. Moreover, it avoids the burning of rice straw in the fields which contributes to air pollution in India and climate change globally. Not only the technical and economical feasibility but also the environmental sustainability of such systems needs to be assessed. The potential effects of implementing community digesters co-digesting cow dung and rice straw on carbon and nutrients flows, human health, resource efficiency and climate change are analyzed by conducting a Substance Flow Analysis and a Life Cycle Assessment. The implementation of the technology is considered at the level of the state of Chhattisgarh. Implementing this scenario reduces the dependency of the rural community to nitrogen and phosphorus from synthetic fertilizers only by 0.1 and 1.6%, respectively, but the dependency of farmers to potassium from synthetic fertilizers by 31%. The prospective scenario returns more organic carbon to agricultural land and thus has a potential positive effect on soil quality. The implementation of the prospective scenario can reduce the health impact of the local population by 48%, increase the resource efficiency of the system by 60% and lower the impact on climate change by 13%. This study highlights the large potential of anaerobic digestion to overcome the aforementioned issues faced by India. It demonstrates the need to couple local and global assessments and to conduct analyses at the substance level to assess the sustainability of such systems.
... This can be satisfied with the low quality of compost only. Otherwise, it might result in over-application of nutrient sources in soil (Martínez-Blanco et al. 2013). According to Boldrin et al. (2009), utilisation of compost to substitute peat as the growing media represents the major saving of GHG emission. ...
Article
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Reduction of landfills and dealing with the waste are among the key elements of the cleaner production and advanced environment policy. Composting represents one of the cleaner technologies in diverting organic waste from landfill. However, it has not been commonly practised in the developing countries due to low economic feasibility and environmental issues that arise from the abuse of compost quality. There are a lack of product standards and an indication of compost quality to govern its market and application. In order to foster public confidence in compost utilisation and as much as possible offset the operating cost, an economic assessment system is needed to benchmark the quality of the compost at a reasonable cost. In this study, a set of composting parameters and their analysis have been reviewed and ranked following their total scores in terms of relation to the agronomic value, technical complexity and analysis cost. The parameters were selected based on different assessment criteria. An assessment system developed on the base of the decision analysis comprises minimal analyses needed to assess the compost quality. The cost savings results from the presented work are illustrated by four scenarios: Scenario 1 served as the baseline to include all the necessary analyses and the remaining three (Scenarios 2, 3 and 4) had been evaluated by the developed assessment system. It is shown that the cost to assess the compost quality was reduced from 17 to 84 % depending on the type of input material and composting performance. The highest cost saving based on the analysis of compost quality reaching 84 % was achieved by Scenario 4 where composting was carried out using the segregated food and landscape waste. The assessment system could be very useful for improving the compost utilisation towards sustainable composting in the developing countries.
... Summary of the potential benefits of compost use-on-land in the short-,mid-, and longterm retrieved from the literature review (adapted fromMartínez-Blanco et al. 2013) ...
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Sources of bio-compost as agro-industrial wastes includes wide range of oil palm wastes viz. waste, biomass, palm kernels, empty fruit bunch, mill effluent, trunk and frond compost. Various composting processes are summarized in brief with distinct reference of oil–palm composting covering aerated static pile, and co-composting with earthworms (vermicomposting). However, in-vessel composting and windrow composting has meritorious advantages in composting. This review article refers to various significant roles played by microorganisms associated. Noteworthy study of bio-compost applications and procedures are correspondingly glosses framework of ecological, economical and agro-ecosystemic benefits.
... Five tons of enriched bio-compost is recommended per hectare land usually applied as basic dose before sowing of crop. WHC water holding capacity, PAW plant available water, ns no significant differences, nad no average data because of complexity of available dataset, -no reported benefits a Change in the indicator b Negative value indicates a decrease in the indicator c The ranges of benefit for three of the more used indicators are presented Table 11.7 Summary of the potential benefits of compost use-on-land in the short-,mid-, and longterm retrieved from the literature review (adapted from Martínez-Blanco et al. 2013) ...
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Africa, with around one billion inhabitants is the world’s second largest and most-populous continent after Asia, the majority of this population live in cities and generate urge amount of municipal solid waste (MSW) which constitute a serious threat to the health of the residents and the environment. Urban and Peri-urban agriculture (UPA), an activity that was developed in African cities in response to the structural adjustments programmes in 1990s is becoming more and more intensive with the continuous raising population. Composting MSW represents an economically, environmentally and socially advantage that could inspire all stakeholders involved in urban planning, within an integrated municipal waste management system, since the MSW that is daily generated has a significant percentage of organic waste that could be easily recycle within the cities in order to close the carbon cycle.
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Despite large efforts there are still methodological challenges to bring life cycle modeling closer to agricultural reality. Here, we focus on the inclusion of the effects occurring between the crops grown in the same agricultural field in temporal succession. These so called crop-rotation effects are caused by changes in physical, chemical and biological properties of the agricultural land over time (presence and availability of different micro and macronutrients, soil structure, soil texture, phytosanitary conditions, presence of weeds, etc.) due to the rotation of crops. Since a huge number of parameters contribute to crop-rotation effects, they cannot be easily measured. Therefore, LCA (Life Cycle Assessment) studies with system boundaries containing only one vegetation period have a limited ability to include these effects — unless explicit modeling measures have been taken to include individual crop-rotation effects. Existing approaches for the inclusion of crop-rotation effects are described, e.g. via transferring certain amounts of nutrients and their environmental burdens to subsequent crops. Still, many crop-rotation effects between crops are not covered in recent LCA methodology; corresponding gaps are identified and described. Examples include reduced input of agrochemicals via improved phytosanitary conditions, stabilization of yields via reduction of harvest failures, improved yields via improved soil texture, soil structure and improved conditions for soil organisms. Overall, most crop-rotation effects are not properly addressed in current LCA practice. Thus, LCA results and the quality of derived recommendations are negatively affected — for example incentives for the (unlimited) removal of crop residues are set based on LCA results without considering potential adverse effects on soil fertility. In other words, these gaps might lead to unintended free-rider problems. A new approach for the modeling of crop-rotation effects is suggested. It consists of six steps. First, align the system boundary during the inventory analysis to the level of the whole crop rotation system; second, determine all inputs of the whole crop rotation; third, do the same for the outputs; fourth, convert all outputs to a common agriculture-specific denominator, the so-called Cereal Unit; fifth, calculate an output-specific allocation share using the ratio of each individual output to the sum of all outputs of the crop rotation; and sixth, apply the allocation shares to the sum of each input-type — resulting in the output-specific allocated input. One major advantage of this approach is the integration of crop-rotation systems into LCA, including all relationships between the individual crops of the crop rotation. Using this approach, LCA practice becomes able to depict crop rotations more accurately and to avoid the current practice of ignoring the effects between individual crops. It might enable LCA to consider the fundamental agricultural principle of crop rotations and to include interactions between one crop and the subsequent crop. Since these crop-rotation effects influence soil fertility, yields and overall sustainability of agricultural systems, the reliability of the evaluation of environmental impacts might be affected. Thus, the ability to consider the entire spectrum of crop rotation effects should be integrated into agricultural LCAs.
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Se determinó el uso de energía de tres sistemas de labranza (L1 convencional, L2 vertical y L3 cero) integrando mejoradores orgánicos, para establecer que manejo tiene un efecto en el corto plazo (dos años) en una menor demanda de energía para las labores. Se realizaron mediciones en el ciclo de cultivo 2012 en un experimento iniciado en 2010 bajo arreglo experimental de parcelas divididas con tres sistemas de labranza como parcelas principales, las subparcelas fueron tres mejoradores de suelo (algas, micorrizas y composta) y una testigo sin mejorador, para un total de 12 unidades experimentales repetidas tres veces. Se midió la fuerza requerida en Newton (N) para las labores de cada sistema e implementos con un dinamómetro integrado al levante hidráulico del tractor. Se calculó la energía en Mega Joules (MJ) necesaria para cada área y sistema de laboreo. Los resultados muestran diferencias significativas en las energías medidas entre los sistemas de labranza pero no entre los tratamientos con mejoradores orgánicos. En comparación con L1 y L2, L3 representa una disminución de uso de energía de 87% y 84,5% respectivamente. Estadísticamente no existe diferencia entre la cantidad de energía gastada por la labranza convencional y la labranza vertical sin embargo con esta última se disminuye en 15,6% el uso de energía en relación a la primera. En el corto plazo, la única posibilidad de disminuir la demanda de energía en los sistemas de producción en la zona semiárida es reducir las labores utilizando sistemas de labranza de conservación.
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The need for biofuels is steadily increasing as a result of political strategies and the need for energy security. Biorefineries have the potential to improve the sustainability of biofuels through further recovery of valuable bioproducts and bioenergy. A life cycle assessment (LCA)-based environmental assessment of a Danish biorefinery system was carried out to thoroughly analyze and optimize the concept and address future research. The LCA study was based on case-specific mass and energy balances and inventory data, and was conducted using consequential LCA approach to take into account market mechanisms determining the fate of products, lost opportunities and marginal productions. The results show that introduction of enzymatic transesterification and improved oil extraction procedure result in environmental benefits compared to a traditional process. Utilization of rapeseed straw seems to have positive effects on the greenhouse gases (GHG) footprint of the biorefinery system, with improvements in the range of 9 % to 29 %, depending on the considered alternative. The mass and energy balances showed the potential for improvement of straw treatment processes (hydrothermal pre-treatment and dark fermentation) as well as minor issues related to enzymes utilization in different bio-processes.
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As compost use in agriculture increases, there is an urgent need to evaluate the specific environmental benefits and impacts as compared with other types of fertilizers and soil amendments. While the environmental impacts associated with compost production have been successfully assessed in previous studies, the assessment of the benefits of compost on plant and soil has been only partially included in few published works. In the present study, we reviewed the recent progresses made in the quantification of the positive effects associated to biowaste compost use on land by using life cycle assessment (LCA). A total of nine environmental benefits were identified in an extensive literature review and quantitative figures for each benefit were drawn and classified into short-, mid-, and long-term. The major findings are the following: (1) for nutrient supply and carbon sequestration, the review showed that both quantification and impact assessment could be performed, meaning that these two benefits should be regularly included in LCA studies. (2) For pest and disease suppression, soil workability, biodiversity, crop nutritional quality, and crop yield, although the benefits were proved, quantitative figures could not be provided, either because of lack of data or because the benefits were highly variable and dependent on specific local conditions. (3) The benefits on soil erosion and soil moisture could be quantitatively addressed, but suitable impact assessment methodologies were not available. (4) Weed suppression was not proved. Different research efforts are required for a full assessment of the benefits, apart from nutrient supply and carbon sequestration; additional impact categories—dealing with phosphorus resources, biodiversity, soil losses, and water depletion—may be needed for a comprehensive assessment of compost application. Several of the natural mechanisms identified and the LCA procedures discussed in the paper could be extensible to other organic fertilizers and compost from other feedstocks.
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Soil recycling of urban wastes is revealing as a valuable alternative for its disposal. The quality of the compost from these wastes is a key aspect to reduce environmental hazards. Two composts from municipal solid wastes (MSW): a) a source separated compost from Barcelona (CB), and b) non source-separated compost from Murcia (CM), were evaluated with regard to its use as soil amendment. The study was carried out in experimental plots located in the Murcia Region. The composts were added into the top 20 cm of the soil at two doses: 15 and 25 kg m -2 dry weight. Both composts led to significant improvements in physical, biological and fertility soil properties. However, whereas CB did not show significant changes in the soil heavy metal concentration, the CM led to an increase in soil pollution by heavy metal. The soil salinization also was double with CM treatment. In conclusion, the use of source-separated MSW compost as soil amendment seems an environmentally friendly option. The source separation of MSW was very effective to reduce soil pollution hazards.
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Agronomic value and environmental impact of two composts were evaluated in a three-year field experiment (2002, 2003 and 2004) on alfalfa and cocksfoot in Southern Italy. The effects of Municipal Solid Waste compost (MSW), Olive Pomace Compost (OPC), mineral fertilizer (Min) (phosphorus as 75 kg ha−1 for alfalfa and nitrogen as 50 kg ha−1 for cocksfoot) and an unfertilized treatment (Contr) were compared on crop yield, soil characteristics and environment impact. During the cropping cycles, fresh and dry weights, plant nitrogen status (leaves SPAD readings and petiole nitrate content) and plant total N content were determined for calculating the protein content and the plant N uptake. Moreover, at the beginning and the end of the research, chemical soil characteristics and heavy metal levels were also determined. The results indicated that in cocksfoot fertilized with MSW and OPC composts, the mean cumulative dry weight increased by 20.85 and 16.51%, respectively compared to the control, but it was significantly lower than Min treatment. In the alfalfa crop, the mean cumulative dry weight of Control, MSW and OPC treatments were very similar and lower than mineral fertilizer (−7.86, −7.09 and −10.31%, respectively). At the end of the experiment, (2004) the soil total N increased significantly in alfalfa (from 1.32 to 1.45 g kg−1) while no significant difference was found for the cocksfoot. After three years of compost application, the total soil organic carbon increased significantly in both crops (23.98% for cocksfoot, and 43.17% for alfalfa in respect to the control), indicating that MSW and OPC amendments positively affected the organic matter. Furthermore, total organic carbon (in both crops) and humified organic carbon (in alfalfa) were significantly lower in the Contr treatment than on the MSW and OPC treatments.
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Composting offers an opportunity to recycle food waste as a soil amendment. A three year growth trial was conducted to determine the fertilizer nitrogen (N) replacement value of food waste composts for cool season perennial grass production. Six composts were produced in a pilot-scale project with two composting methods (aerated static pile and aerated, turned windrow). The aerated, turned windrow method simulated “agitated bay” composting systems, which utilize routine mechanical agitation. Compost bulking agents included yard trimmings, yard trimmings + mixed paper waste, and wood waste + sawdust. Finished composts had Kjeldahl N concentrations ranging from 10 to 18 g N/kg. For the growth trial, composts were incorporated into the top eight to 10 cm of a sandy loam soil at application rates of approximately 155 Mg/ha (about 7 yd3/1000 ft2). Tall fescue (Festuca arundinacea Schreb. ‘A.U. Triumph’) was seeded after compost incorporation, and was harvested repeatedly at a late vegetative growth stage (April to November; approx. 35 days regrowth between harvests). Grass yield and grass N uptake did not respond to compost application during the first year. During the second and third years after application, composts were a consistent source of slow-release N. They supplied the fertilizer N equivalent of 0.70 kg N/ha/day over a 140-day period (April to August) in both years. The N supplied by composts in the second and third year after application was valued at $0.70 to $1.90 per dry tonne (Mg) compost per year, using a fertilizer N cost of $1/kg N. Food waste composts with significant slow-release N properties were produced with either the aerated static pile composting method or the aerated, turned windrow method. Composts with higher N concentrations had higher fertilizer N replacement value. The slow release N supplied by food waste composts is ideally suited for urban landscapes, where a moderate, consistent rate of plant growth is highly desirable.
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Aims and Scope. Land use by agriculture, forestry, mining, house-building or industry leads to substantial impacts, particularly on biodiversity and on soil quality as a supplier of life support functions. Unfortunately there is no widely accepted assessment method so far for land use impacts. This paper presents an attempt, within the UNEP-SETAC Life Cycle Initiative, to provide a framework for the Life Cycle Impact Assessment (LCIA) of land use. Main Features. This framework builds from previous documents, particularly the SETAC book on LCIA (Lindeijer et al. 2002), developing essential issues such as the reference for occupation impacts; the impact pathways to be included in the analysis; the units of measure in the impact mechanism (land use interventions to impacts); the ways to deal with impacts in the future; and bio-geographical differentiation. Results. The paper describes the selected impact pathways, linking the land use elementary flows (occupation; transformation) and parameters (intensity) registered in the inventory (LCI) to the midpoint impact indicators and to the relevant damage categories (natural environment and natural resources). An impact occurs when the land properties are modified (transformation) and also when the current man-made properties are maintained (occupation). Discussion. The size of impact is the difference between the effect on land quality from the studied case of land use and a suitable reference land use on the same area (dynamic reference situation). The impact depends not only on the type of land use (including coverage and intensity) but is also heavily influenced by the bio-geographical conditions of the area. The time lag between the land use intervention and the impact may be large; thus land use impacts should be calculated over a reasonable time period after the actual land use finishes, at least until a new steady state in land quality is reached. Conclusion. Guidance is provided on the definition of the dynamic reference situation and on methods and time frame to assess the impacts occurring after the actual land use. Including the occupation impacts acknowledges that humans are not the sole users of land. Recommendations and Perspectives. The main damages affected by land use that should be considered by any method to assess land use impacts in LCIA are: biodiversity (existence value); biotic production potential (including soil fertility and use value of biodiversity); ecological soil quality (including life support functions of soil other than biotic production potential). Biogeographical differentiation is required for land use impacts, because the same intervention may have different consequences depending on the sensitivity and inherent land quality of the environment where it occurs. For the moment, an indication of how such task could be done and likely bio-geographical parameters to be considered are suggested. The recommendation of indicators for the suggested impact categories is a matter of future research.
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Environmental burdens of four different full-scale facilities treating source-separated organic fraction of Municipal Solid Wastes (OFMSW) have been experimentally evaluated. The studied facilities include different composting technologies and also anaerobic digestion plus composting. Home composting, as an alternative to OFMSW management, was also included in the study. Energy (electricity and diesel), water consumption and emissions of volatile organic compounds (VOC), ammonia, methane and nitrous oxide have been measured for each process. Energy consumption ranged between 235 and 870 MJ Mg OFMSW−1 while the emissions of the different contaminants considered per Mg OFMSW were in the range of 0.36–8.9 kg VOC, 0.23–8.63 kg NH3, 0.34–4.37 kg CH4 and 0.035–0.251 kg N2O, respectively. Environmental burdens of each facility are also analyzed from the point of view of process efficiency (i.e. organic matter stabilization degree achieved, calculated as the reduction of the Dynamic Respiration Index (DRI) of the waste treated). This study is performed through two new indices: Respiration Index Efficiency (RIE), which includes the reduction in the DRI achieved by the treatment process and Quality and Respiration Index Efficiency (QRIE), which also includes the quality of the end product. Finally, a Life Cycle Assessment is performed using the Respiration Index Efficiency (RIE) as the novel functional unit instead of the classical LCA approach based on the total mass treated.
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Organic fertilizer produced by composting 62% town wastes, 21% sewage sludge and 17% sawdust by volume, was applied at the rates of 0 (control), 75, 150 and 300 m3 ha−1 to loamy and clay soils, in order to investigate its potential for soil improvement. The experiments were conducted in areas characterised by a semi-arid climate. The chemical properties of the soils were affected directly by the amendment compost. The physical properties of the amended soils were improved in all cases as far as the saturated and unsaturated hydraulic conductivity, water retention capacity, bulk density, total porosity, pore size distribution, soil resistance to penetration, aggregation and aggregate stability, were concerned. In most of the cases the improvements were proportional to the application rates of the compost and they were greater in the loamy soil than in the clay soil.
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Soil ecosystem functions have significantly deteriorated due to agricultural intensification with dramatic consequences on carbon loss, loss of soil biodiversity, erosion, compaction as well as unsustainable use of water and mineral resources. Sustainable agricultural practices are necessary if we are to face the challenge of food security while preserving the integrity of soil and aquatic ecosystems. Conservation agriculture, which is comprised of zero or minimum tillage, carbon amendments and crop rotations, holds great promise in delivering higher yields, using water and soil resources in a sustainable manner and increasing soil biodiversity. This article presents a synthesis of current knowledge on soil ecosystem processes and modeling with a focus on carbon and nitrogen dynamics and their link to soil structure, and proposes a conceptual framework for model parameterization capable of predicting critical soil functions and potential shifts.
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Anaerobically digested biosolid and the organic fraction from a municipal solid waste were surface applied at 80 Mg ha-1 to a degraded highly carbonated soil (Rensic Leptosol) from the southeast of Madrid (Spain) to determine the effects of these organic wastes on soil physical and chemical properties. After one year of the waste application, soil samples at 0-15 cm and 15-30 cm depths were taken. The structure of the soil was slightly improved by a small decrease in particle and bulk densities, an increase in water retention accompanied by an increase of organic matter. Waste application also increased the amorphous iron oxide contents and the total heavy metals in the soil in particular the Cu and Zn contents in the surface level. The significative increase of Zn in the subsurface level suggests that the Zn migrated in this soil profile, probably because of its affinity with organic matter soluble fractions.
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The role of nitrogen (N) as yield-limiting factor was evaluated over a 2-year period in tomato under conventional and organic management. Three N fertilization rates (0, 100, 200 kg N ha-1) and three tomato cultivars were compared under organic and conventional cropping systems. Yield response to organic system was different between the two years. In the second year marketable yield in the conventional system was significantly higher than in the organic system. Increasing nitrogen fertilization from 0 to 200 kg N ha-1 resulted in tomato yield increase and fruit quality improvement. Significant differences for nutritional quality between organically and conventionally grown tomatoes were observed. Total carotenoids concentration and antioxidant activity increased in organic tomatoes.
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A study was conducted to compare the nitrogen (N) availability of blends of biosolids compost or municipal refuse-biosolids cocompost with urea(U) or NH4N03(N) fertilizers to fertilizer alone on growth and N uptake of tall fescue (Festuca arundinacea L.). Blends which provided 0, 16.7, 33 or 50 % of the N kg-1 application rate as compost N and 100, 83.3, 67 or 50% as fertilizer N were added to Sassafras soil (Typic Hapludults). Study 1 had a 150 mg N kg -1 application rate and study 2 had 120 mg N kg-1. Compost N mineralization was assumed to be 10% and comparisons were made on a fertilizer N equivalency basis. Yield and N uptake from blends of biosolids compost or municipal refuse-biosolids co-compost and NH4NO3 were not different from the equivalent NH4NO3 treatment. In study 2 which compared blends of biosolids compost and either urea (U) or NH 4NO3CN) to fertilizer alone, yield and N uptake were not different from the equivalent fertilizer treatment with one exception. Yield and N uptake from 50% NH4NO3 -50% biosolids compost blend were greater than the equivalent 66 mg NH4NO3-N kg-1 treatment. Compost fertilizer equivalent based on a 10% organic nitrogen mineralization rate was accurate in blends with fertilizer. Greater yield and N uptake than predicted were seen when NH4NO3 content in the fertilizer compost blend was below 88 mg N kg and did not mask the additional benefit of compost amendment. When an approximate N mineralization rate for compost is known, it is possible to formulate blends with fertilizer that will predictably support crop growth.
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For the last 50 years, the consensus view among researchers has been that organic matter (OM) has little or no effect on the available water capacity (AWC) of soil. The historical development of this viewpoint is traced, and it is argued that the literature on this subject has been misconstrued. In addition to a critical review of the literature, published data were evaluated to access the effect of OM content on the AWC of surface soil. In all texture groups, as OM content increased from 0.5 to 3%, AWC of the soil more than doubled. Soil OM is an important determinant of AWC because, on a volume basis, it is a significant soil component. -from Author
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Agronomic value and environmental impacts of three composts (a biowaste compost, BIO; a municipal solid waste compost, MSW and a compost made from green wastes co-composted with sewage sludge, GWS) are compared to those of farmyard manure (FYM) in a long-term field experiment located in Feucherolles (Yvelines, France) and initiated in 1998. The first compost spreading occurred in October 1998 and maize was sown in spring 1999. Short composting time (in MSW) induced a large residual biodegradability of the organic matter and a transitory nitrogen (N) immobilisation after compost addition to soil followed by a faster organic N mineralisation than in more stabilised compost. The lowest concentrations of heavy metals were observed in the BIO compost in relation with the sorting of the composted wastes. Very low concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were detected in the composts. Soil (loamy clay) was analysed before starting the experiment. All heavy metals concentrations were lower than the average measured in French soils. Lead and mercury presented the largest variability (25 and 16%, respectively). Organic pollutant (PAHs and PCBs) concentrations were also low. A gradient of concentration was observed with up to 126% variability of the initial concentrations. The heavy metal input associated with compost spreading represented less than 5% of the initial stock present in the soil. The inputs of organic pollutants were proportionally larger but the evaluation of the other sources of contamination (aerial origin, for example) would be necessary to quantify the impacts of composts. Less than 5% of compost nitrogen and phosphorous was used by the plants. No cadmium, lead or chromium were found in the grains. No significant effect of the organic amendments was observed on the heavy metal content in grains and stems.
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Numerous microorganisms are involved in the composting process, but their precise roles are often unknown. Compost microorganisms are influenced by the composition of the substrate and by the temperature in the compost pile. In addition, different microorganisms also influence each other, e.g. through competition. In the first phase of composting, microbial activity increases drastically, leading to a rise in temperature. The initial bacterial dominance is replaced by a fungal one during compost maturation. Compost management aims to achieve favourable conditions for beneficial and unfavourable conditions for harmful microorganisms. The type of input substrate, the size of compost piles, the frequency of turning, particle size, aeration and moistening all affect the microbial processes. They influence microorganisms mainly by affecting nutrient, oxygen and water supply. Sometimes, composts are inoculated with selected microorganisms. Harmful microorganisms are introduced into the compost mainly with the input substrate. They are mainly inactivated by high temperatures, but other mechanisms of inactivation have also been demonstrated, e.g. certain plant-derived compounds and antagonistic interactions. Beneficial microorganisms are capable of outcompeting harmful ones during the process and/or have a beneficial effect on crops after field application. Application of compost increases the microbial activity of soils, and crops are less sensitive to diseases after compost application (disease suppressiveness); the mechanisms are largely unknown. Better knowledge in this field would certainly allow optimizing the composting process to enhance disease suppressiveness.
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Sandy, infertile soils can benefit from the addition of organic waste amendments. Annual applications of organic wastes for as long as 4 yr increased soil organic matter content, decreased soil bulk density, and increased soil water retention of a coarse-textured soil. However, soil water-holding capacity was not necessarily increased, and there was a limited effect on soil cation exchange capacity. Key words: Cation exchange capacity, water retention, soil pH, soil organic matter, soil bulk density
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Purpose The spatial dependency of pesticide emissions to air, surface water and groundwater is illustrated and quantified using PestLCI 2.0, an updated and expanded version of PestLCI 1.0. Methods PestLCI is a model capable of estimating pesticide emissions to air, surface water and groundwater for use in life cycle inventory (LCI) modelling of field applications. After calculating the primary distribution of pesticides between crop and soil, specific modules calculate the pesticide’s fate, thus determining the pesticide emission pattern for the application. PestLCI 2.0 was developed to overcome the limitations of the first model version, replacement of fate calculation equations and introducing new modules for macropore flow and effects of tillage. The accompanying pesticide database was expanded, the meteorological and soil databases were extended to include a range of European climatic zones and soil profiles. Environmental emissions calculated by PestLCI 2.0 were compared to results from the risk assessment models SWASH (surface water emissions), FOCUSPEARL (groundwater via matrix leaching) and MACRO (groundwater including macropore flow, only one scenario available) to partially validate the updated model. A case study was carried out to demonstrate the spatial variation of pesticide emission patterns due to dependency on meteorological and soil conditions. Results Compared to PestLCI 1.0, PestLCI 2.0 calculated lower emissions to surface water and higher emissions to groundwater. Both changes were expected due to new pesticide fate calculation approaches and the inclusion of macropore flow. Differences between the SWASH and FOCUSPEARL and PestLCI 2.0 emission estimates were generally lower than 2 orders of magnitude, with PestLCI generally calculating lower emissions. This is attributed to the LCA approach to quantify average cases, contrasting with the worst-case risk assessment approach inherent to risk assessment. Compared to MACRO, the PestLCI 2.0 estimates for emissions to groundwater were higher, suggesting that PestLCI 2.0 estimates of fractions leached to groundwater may be slightly conservative as a consequence of the chosen macropore modelling approach. The case study showed that the distribution of pesticide emissions between environmental compartments strongly depends on local climate and soil characteristics. Conclusions PestLCI 2.0 is partly validated in this paper. Judging from the validation data and case study, PestLCI 2.0 is a pesticide emission model in acceptable accordance with both state-of-the-art pesticide risk assessment models. The case study underlines that the common pesticide emission estimation practice in LCI may lead to misestimating the toxicity impacts of pesticide use in LCA.
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A two-year study was conducted in 2002-2003 (season one) and 2003-2004 (season two) at a seepage irrigated vegetable farm in south Florida to investigate the effects of soil organic amendment (composted yard waste) on movement of water in a sandy soil. Season one result showed that for the same water table depth, soil moisture content in the compost field was higher than the noncompost field in the root zone (top 20 cm). The increased soil moisture was attributed to the increased upflux due to increased capillary rise. Increased capillary rise was a result of increased organic matter content of the soil from compost application. After a rainfall event, soil moisture at 10 cm depth in the compost field responded rapidly, suggesting a higher extent of capillary fringe in the compost field compared to the noncompost field, which did not show the similar response. Another addition of compost further enhanced the soil moisture effect in season two. Season two results showed a higher difference between compost and noncompost soil moisture from the previous season. Results from the study showed that the addition of compost can help in maintaining the same level of soil moisture with a lower water table compare to the noncompost field. A lower water table in the compost field can result in higher retention of rainfall in the soil compared to the noncompost field, which in turn can reduce runoff, deep percolation, and seepage losses and achieve water conservation.
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Two different composts, a cattle manure compost (CMC) and a municipal waste compost (MWC), were applied at a rate of five percent or 15 percent to two soils, differing in their mineralization capacity, and incubated for 33 weeks at 30°C and optimal soil-water content. Periodically, CO2 evolution rates and inorganic N concentrations were measured in the soils. The rate of compost-N recovered as inorganic N was independent of the soil and compost application rate. The recovery after 33 weeks (w) was 22 percent of MWC-N and 23 to 27 percent of CMC-N, of which 13 percent was initially inorganic. The recovery of compost-C as CO2 depended on the compost application rate and to a lesser extent on the soil, reaching values of 13 to 15 percent and eight percent for the low and high application rates, respectively.
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Despite the fundamental role of ecosystem goods and services in sustaining human activities, there is no harmonized and internationally agreed method for including them in life cycle assessment (LCA). The main goal of this study was to develop a globally applicable and spatially resolved method for assessing land use impacts on the erosion regulation ecosystem service. Soil erosion depends much on location. Thus, unlike conventional LCA, the endpoint method was regionalized at the grid cell level (5 arcmin, approximately 10 x 10 km(2)) to reflect the spatial conditions of the site. Spatially explicit characterization factors were not further aggregated at broader spatial scales. Life cycle inventory data of topsoil and topsoil organic carbon (SOC) losses were interpreted at the endpoint level in terms of the ultimate damage to soil resources and ecosystem quality. Human health damages were excluded from the assessment. The method was tested on a case study of five 3-year agricultural rotations, two of them with energy crops, grown in several locations in Spain. A large variation in soil and SOC losses was recorded in the inventory step, depending on climatic and edaphic conditions. The importance of using a spatially explicit model and characterization factors is shown in the case study. The regionalized assessment takes into account the differences in soil erosion-related environmental impacts caused by the great variability of soils. Taking this regionalized framework as the starting point, further research should focus on testing the applicability of the method through the complete life cycle of a product and on determining an appropriate spatial scale at which to aggregate characterization factors in order to deal with data gaps on the location of processes, especially in the background system. Additional research should also focus on improving the reliability of the method by quantifying and, insofar as it is possible, reducing uncertainty.
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Integrated Weed Management in arable crops relies on the combination of various measures for preventing, avoiding and suppressing weeds, with the aim of reducing the reliance on herbicides and their environmental impacts. As IWM requires potentially deep changes in the cropping systems, modifying e.g. the crop sequence, the strategies for soil tillage and eventually introducing mechanical weeding, it is important to perform comprehensive evaluations of IWM-based cropping system prototypes. In this study, a Life Cycle Assessment method was used to compute several environmental impacts for four variants of IWM-based cropping system tested over a pluri-annual experiment, and compared with a standard reference. When expressed per unit of cultivated area, most environmental indicators were improved in IWM-based systems, including the energy input, greenhouse gas emission, eutrophication and acidification, and ecotoxicity and human toxicity. In-field fuel consumption was a rather minor contribution to the overall energy demand and to global warming. The ranking of the tested cropping systems was different when the indicators were expressed per unit of harvested agricultural goods or per unit of farmer's income. With these two functional units, the differences among systems tended to be weaker, and some indicators of environmental impacts were higher in IWM-based systems. Indicators focusing on biodiversity and soil quality displayed few differences among systems.
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Soil organic matter improves the physical, chemical and biological properties of soil, and crop residue recycling is an important factor influencing soil organic matter levels. We studied the impact of continuous application of rice straw compost either alone or in conjunction with inorganic fertilizers on aggregate stability and distribution of carbon (C) and nitrogen (N) in different aggregate fractions after 10 cycles of rice–wheat cropping on a sandy loam soil at Punjab Agricultural University research farm, Ludhiana, India. Changes in water stable aggregates (WSA), mean weight diameter (MWD), aggregate-associated C and N, total soil C and N, relative to control and inorganically fertilized soil were measured. Total WSA were significantly (p = 0.05) higher for soils when rice straw compost either alone or in combination with inorganic fertilizers was applied as compared to control. The application of rice straw compost either alone or in combination with inorganic fertilizers increased the macroaggregate size fractions except for 0.25–0.50 mm fraction. The MWD was significantly (p = 0.05) higher in plots receiving rice straw compost either alone at 8 tonnes ha−1 (0.51 mm at wheat harvest and 0.41 mm at rice harvest) or at 2 tonnes ha−1 in combination with inorganic fertilizers (0.43 and 0.38 mm) as compared to control (0.34 and 0.33 mm) or inorganically fertilized plots (0.33 and 0.31 mm). The macroaggregates had higher C and N density compared to microaggregates. Application of rice straw compost at 2 tonnes ha−1 along with inorganic fertilizers (IN + 2RSC) increased C and N concentration significantly over control. The C and N concentration increased further when rice straw compost at 8 tonnes ha−1 (8RSC) was added. It is concluded that soils can be rehabilitated and can sustain the soil C and N levels with the continuous application of rice straw compost either alone or in combination with inorganic fertilizers. This will also help in controlling the rising levels of atmospheric carbon dioxide.
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The environmental impact of the water consumption of four typical crop rotations grown in Spain, including energy crops, was analyzed and compared against Spanish agricultural and natural reference situations. The life cycle assessment (LCA) methodology was used for the assessment of the potential environmental impact of blue water (withdrawal from water bodies) and green water (uptake of soil moisture) consumption. The latter has so far been disregarded in LCA. To account for green water, two approaches have been applied: the first accounts for the difference in green water demand of the crops and a reference situation. The second is a green water scarcity index, which measures the fraction of the soil‐water plant consumption to the available green water. Our results show that, if the aim is to minimize the environmental impacts of water consumption, the energy crop rotations assessed in this study were most suitable in basins in the northeast of Spain. In contrast, the energy crops grown in basins in the southeast of Spain were associated with the greatest environmental impacts. Further research into the integration of quantitative green water assessment in LCA is crucial in studies of systems with a high dependence on green water resources.
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ABSTRACT,system as opposed to a more intensive conventional tillage system can favour fungi (Frey et al., 1999). The Fungi are capable of nitrification and denitrification and often potential for fungi to produce,N2O has been,shown,in dominate the microbial biomass of temperate grassland soils. We de- termined the contributions of bacteria and fungi to N2O and N2 produc- two studies using woodland soils (Castaldi and Smith, tion in a grassland soil from Northern Ireland by com,N gas-flux method (Mosier and Schimel, 1993). By has been extensively studied in several bacteria (Zumft, labeling the NH4 and NO3 pools, we tested the hypothe- 1997). By the 1970s, it became clear that denitrification sis that fungi produce,N2O and N2 solely by the reduction is a function of eukaryotes,as well as bacteria. Yeasts of NO3 and not by oxidation of NH4. (Tsuruta et al., 1998) and filamentous fungi (Bollag and Tung, 1972; Shoun et al., 1992) have been shown to be
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Soil aggregation is of great importance in agriculture due to its positive effect on soil physical properties, plant growth and the environment. A long-term (1996–2008) field experiment was performed to investigate the role of mycorrhizal inoculation and organic fertilizers on some of soil properties of Mediterranean soils (Typic Xerofluvent, Menzilat clay–loam soil). We applied a rotation with winter wheat (Triticum aestivum L.) and maize (Zea mays L.) as a second crop during the periods of 1996 and 2008. The study consisted of five experimental treatments; control, mineral fertilizer (300–60–150kgN–P–Kha−1), manure at 25tha−1, compost at 25tha−1 and mycorrhiza-inoculated compost at 10tha−1 with three replicates. The highest organic matter content both at 0–15cm and 15–30cm soil depths were obtained with manure application, whereas mineral fertilizer application had no effect on organic matter accumulation. Manure, compost and mycorrhizal inoculation+compost application had 69%, 32% and 24% higher organic matter contents at 0–30cm depth as compared to the control application. Organic applications had varying and important effects on aggregation indexes of soils. The greatest mean weight diameters (MWD) at 15–30cm depth were obtained with manure, mycorrhiza-inoculated compost and compost applications, respectively. The decline in organic matter content of soils in control plots lead disintegration of aggregates demonstrated on significantly lower MWD values. The compost application resulted in occurring the lowest bulk densities at 0–15 and 15–30cm soil depths, whereas the highest bulk density values were obtained with mineral fertilizer application. Measurements obtained in 2008 indicated that manure and compost applications did not cause any further increase in MWD at manure and compost receiving plots indicated reaching a steady state. However, compost with mycorrhizae application continued to significant increase (P
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Common agricultural practices such as excessive use of agro-chemicals, deep tillage and luxury irrigation have degraded soils, polluted water resources and contaminated the atmosphere. There is increasing concern about interrelated environmental problems such as soil degradation, desertification, erosion, and accelerated greenhouse effects and climate change. The decline in organic matter content of many soils is becoming a major process of soil degradation, particularly in European semi-arid Mediterranean regions. Degraded soils are not fertile and thus cannot maintain sustainable production. At the same time, the production of urban and industrial organic waste materials is widespread. Therefore, strategies for recycling such organic waste in agriculture must be developed. Here, we review long-term experiments (3–60 years) on the effects of organic amendments used both for organic matter replenishment and to avoid the application of high levels of chemical fertilizers. The major points of our analysis are: (1) many effects, e.g. carbon sequestration in the soil and possible build-up of toxic elements, evolve slowly, so it is necessary to refer to long-term trials. (2) Repeated application of exogenous organic matter to cropland led to an improvement in soil biological functions. For instance, microbial biomass carbon increased by up to 100% using high-rate compost treatments, and enzymatic activity increased by 30% with sludge addition. (3) Long-lasting application of organic amendments increased organic carbon by up to 90% versus unfertilized soil, and up to 100% versus chemical fertilizer treatments. (4) Regular addition of organic residues, particularly the composted ones, increased soil physical fertility, mainly by improving aggregate stability and decreasing soil bulk density. (5) The best agronomic performance of compost is often obtained with the highest rates and frequency of applications. Furthermore, applying these strategies, there were additional beneficial effects such as the slow release of nitrogen fertilizer. (6) Crop yield increased by up to 250% by long-term applications of high rates of municipal solid waste compost. Stabilized organic amendments do not reduce the crop yield quality, but improve it. (7) Organic amendments play a positive role in climate change mitigation by soil carbon sequestration, the size of which is dependent on their type, the rates and the frequency of application. (8) There is no tangible evidence demonstrating negative impacts of heavy metals applied to soil, particularly when high-quality compost was used for long periods. (9) Repeated application of composted materials enhances soil organic nitrogen content by up to 90%, storing it for mineralization in future cropping seasons, often without inducing nitrate leaching to groundwater.
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The handling, processing, and disposal of solid waste have reached such proportions in the USA as to constitute one of our major environmental problems. Over 480 million metric tons of solid waste are discarded annually by American citizens. In the past, most of this waste was burned in open dumps or deposited in mismanaged landfills. Because of air and water pollution, more satisfactory methods must be developed for solid waste disposal. Composting with efficient machinery under sanitary conditions shows promise in helping to solve this problem. The end product of composting has value as a soil amendment and contains nutrients which are available for plant use. The objective of this study was to evaluate a pelletized compost of much improved physical conditions as compared to other composted municipal refuse. Pelletized compost was used in a greenhouse study as a soil amendment and plant nutrient source after incorporation in Arredondo sand. The application of 8 metric tons/ha of compost increased the yields of two sorghum (Sorghum bicolor L. Moench) crops as compared to the control. Also, the highest rate of compost (64 metric tons/ha) produced higher yields as compared 10-4.4-8.3 fertilizer at 2 tons/ha. Uptake of all plant nutrients measured, except for Mn, was increased by compost applications. In addition, water retention and cation exchange capacity of the Arredondo sand were generally increased by compost applications. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
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De Cauwer B, Van Den Berge K, Cougnon M, Bulcke R & Reheul D (2010). Weed seedbank responses to 12 years of applications of composts, animal slurries or mineral fertilisers. Weed Research50, 425–435. Fertiliser amendments can impact weed populations in a variety of ways. This study evaluated the effects of 12-year-long applications of different fertilisation systems on size and composition of the weed seedbank in a conventionally managed maize monoculture field. Fertilisation systems included all factorial combinations of two dairy cattle slurry rates, three vegetable, fruit and garden waste compost rates, and three synthetic N fertiliser rates. Soil samples were taken in each subplot in May 2008 after sowing and prior to herbicide application. Residues recovered from soil samples were tested for weed seedling emergence to characterise soil seedbanks. Total weed seedbank density was affected by mineral N fertilisation, but not by compost or animal slurry application. Weed seedbank composition was related to compost amendment and mineral N fertilisation. Annual compost amendments reduced seedbank density of some persistent species (e.g., Chenopodium album and Solanum nigrum) irrespective of mineral N fertilisation. Compost is a promising tool for incorporation into integrated weed control strategies aimed at reducing weed seedbank persistence.
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Crusting and erosion of cultivated soils result from aggregate breakdown and the detachment of soil fragments by rain, and the susceptibility of soil to these processes is often inferred from measurements of aggregate stability. Here, theories of aggregate breakdown are reviewed and four main mechanisms (i.e. slaking, breakdown by differential swelling, mechanical breakdown by raindrop impact and physico–chemical dispersion) are defined. Their relative importance depends on the nature of the rain, as well as on the soil's physical and chemical properties. The relations between aggregate breakdown, crusting and water erosion are analysed, and existing methods for the assessment of aggregate stability are reviewed. A unified framework for the measurement of aggregate stability is proposed to assess a soil's susceptibility to crusting and erosion. It combines three treatments having various wetting conditions and energies (fast wetting, slow wetting, and stirring after pre-wetting) and measures the resulting fragment size distribution after each treatment. It is designed to compare different soils, or different climatic conditions for a given soil, not to compare time-dependent changes in that soil.
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Light textured sandy soils in northeast Thailand are often highly weathered and degraded resulting in low nutrient and water holding capacities. The latter is further complicated by the structural instability of these soils. Field based soil amelioration studies were undertaken in order to evaluate local traditional practices currently adopted by farmers and innovative approaches to improve the productivity of these soils. The treatments included: composted leaf litter, termite mound material, and bentonite. In the present study, physical properties associated with water holding capacity and soil structural stability of an upland soil of the Satuk series in Northeast Thailand were investigated two years after the application of these amendments. Although changes in silt and clay fraction were small, the application of these amendments enhanced porosity and altered the pore size distribution resulting in an increase in the available water content for crop growth. In particular, increases in the available water content were remarkably higher under termite mound material (0.21 m m) and bentonite (0.19 m m) treatments when compared to the control (0.14 m m). However, soil structural stability remained poor for the compost and termite mound material treatments, while the structural stability was enhanced for the bentonite treatment. Enhanced soil structural stability observed in the bentonite treatment accounted for the persistence in increased water holding capacity, and this will have positive benefits to the rainfed cropping systems that are susceptible to periodic drought stress, thereby reducing risk of crop failure associated with low water holding capacity.
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Accumulation of municipal solid wastes, such as household solid waste, can be rated as a harmful, if not critical, pollution problem. However, if these wastes can be composted and the end product used as soil organic amendment or fertilizer, this may represent one of the alternatives for achieving the goal of ensuring integrated and sustainable waste management. The objective of the present work is to evaluate the nitrogen fertilizing value of household solid waste compost in two soils of Morocco with contrasting properties: a sandy soil and a loamy-clay soil. The compost used in this study was prepared by aerobic biodegradation using the organic fraction after its separation from the noncompostable materials. A study of nitrogen availability of the compost was carried out in a Soil - Compost - Crop system under greenhouse conditions using lettuce as a test crop. Four increasing compost rates of 0, 10, 20 and 30 tons/ha were applied to the soils. The recommended mineral fertilizer rate by the Agricultural Extension Service for lettuce and its half values constituted additional treatments. The results show a high stock of mineral nitrogen in the loamy-clay soil before crop installation. Unlike the loamy-clay soil, the sandy soil generated a better yield increase and a better response to mineral fertilizers. The effect of compost rate on nitrogen mineralization was significant in the two studied soils. The quantities of mineralized nitrogen of the compost varied between 15 and 24% of the compost total nitrogen applied to the sandy and the loamy-clay soils during the lettuce growing season. Therefore the use of household solid waste compost as soil amendment constitutes a beneficial alternative in Mediterranean soils because it permits the generation of a high nitrogen fertilizing value.
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Under the environmental conditions of the central sector of Saudi Arabia, El-Gassim region, two field experiments were conducted on a sandy soil in the winter seasons of 1990–1991 and 1991–1992. Town refuse compost, at rates of 0·0, 16·5, 33·0, 49·5 and 66·0 t ha−1, was incorporated into the soil to a depth of 10 cm. The effect of the compost in optimizing the physical conditions of the sandy soil, as well as growth, nutrient uptake, grain and straw yields and water use efficiency of wheat were studied. The results indicated that the various application rates through the two seasons of growth were significantly correlated with improvements in the physical properties. The manure stimulated suitable conditions for plant growth and development, and acted as a good substratum for microbial activity. This was positively reflected in the magnitudes of dry weight, biological crop yield, root weight, nutrient uptake, straw and grain yields, grain protein yield and water use efficiency. Generally, 33·0 t ha−1 of the manure was considered to be the optimum application rate under the conditions of the present investigation. Moreover, the soil physical properties were significantly correlated with the results obtained for straw, grain and protein yields of wheat during both seasons. Multiple regression analysis revealed that the degree of aggregation is the important soil property for wheat production in sandy soils.