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Abstract: Organic farming is under constant pressure to reinvent itself by adopting new technologies. This article examines the role of precaution in organic farmers’ assessments of new technologies, and asks how their assessments draw on different types of knowledge. The article further explores how knowledge type compares to the role of knowledge and precaution expressed in the principles of organic farming as defined by the organic movement organisation, IFOAM. Results from a study of the introduction of sewage sludge as an alternative source of nutrients in organic agriculture are presented. Empirically, this case‐study builds on the analysis of five focus groups made up of Danish organic farmers. While some farmers called for precaution, supporting this with claims about lacking knowledge, others trusted the authorities and accepted sewage sludge provided it was officially approved for organic use. Our analysis suggests that when assessing new technologies Danish organic farmers rely on scientific knowledge and do not automatically draw on the experiential knowledge they possess and employ in other contexts. It is concluded that if IFOAM wishes include farmers’ experiential knowledge as a basis for decisions about precaution, there is a need to develop instruments making it possible to tap into this knowledge. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is broadly recognised as an important parameter affecting soil quality, and can therefore contribute to improving a number of soil properties that influence crop yield. Previous research generally indicates that soil organic carbon has positive effects on crop yields, but in many studies it is difficult to separate the effect of nutrients from the effect of SOC in itself. The aim of this study was to analyze whether the SOC content, in itself, has a significant effect on potential yields of commonly grown cereals across a wider range of soil types in Denmark. The study draws on historical data sets from the Danish national field trials consisting of 560 winter wheat ( Triticum aestivum L.) trials and 309 spring barley ( Hordeum vulgare L.) trials conducted over the past 20 and 17 years, respectively. We hypothesised that for these two crops, the potential grain yield, the yield with no fertiliser N application and the N use efficiency would be positively affected by SOC level. A statistical model was developed to explore relationships between SOC and potential yield, yields at zero N application and N use efficiency (NUE). The model included a variety of variables and aimed to elucidate the sole effect of SOC by controlling for potential confounding variables. No significant effect of SOC on potential winter wheat was found, whilst for spring barley, only for the course sandy loam soil type was a borderline significantly positive effect of SOC on potential yields found. The relationship between unfertilized plot yields and SOC was positive for winter wheat, although not significant, whilst for spring barley a significant positive effect of SOC was found only for the coarse sandy soil type, and a borderline significant positive effect of SOC was found for the coarse sandy loam soil type. A significant negative relationship was found between SOC and NUE for both winter wheat and spring barley. Based on the large dataset analyzed, we cautiously challenge the importance of SOC in contributing to crop productivity in contexts with similar soils and climate, and we speculate that in situations where nutrient limitation does not occur, SOC levels above 1% may be sufficient to sustain yields. In light of the findings presented in this study, further work should be conducted which can further elucidate the effect of SOC on yields. [ABSTRACT FROM AUTHOR]

Taking departure in the theory of resilience in social-ecological systems, we present an analysis and discussion of how resilience theory can be applied to agroecosystems. Building on the premise that agroecosystems are too complex for resilience to be measured in any precise manner, we delineate behavior-based indicators of resilience within agroecosystems. Based on a review of relevant literature, we present and discuss an index of 13 such indicators, which, when identified in an agroecosystem, suggest that it is resilient and endowed with the capacity for adaptation and transformation. Absence of these indicators identifies points of intervention for managers and stakeholders to build resilience where there is vulnerability. The indicators encompass various phases in the adaptive cycle and seek to link core aspects of social-ecological systems. We stress the strong societal need for building resilience in agroecosystems and advocate for a broader way of evaluating resilience in agroecosystems. [ABSTRACT FROM AUTHOR]

Certified organic agriculture stipulates a range of principles and standards, which govern farmer practices. The recent global expansion of organic agriculture has raised new challenges for organic agriculture, particularly whether management practices in organic farms are subject to the forces of conventionalisation. We studied changes in agroecological practices in certified organic farms in China, Brazil and Egypt. The study takes departure in the conventionalisation hypothesis and the analysis is framed using organic and agroecological principles. The study focuses on agroecological design principles, inherent to organic agriculture, of diversity in crop production, pest, disease and weed management, and soil fertility management. The research design was as a multiple case study of five cases in China, Brazil and Egypt. We show that the adoption of organic agriculture has induced fundamental changes in organic farmer management practices, although agroecological practices of organic farmers do not fulfil organic principles. The forces of conventionalisation exert a strong influence on changes in organic farmer practices. Organic 'niche' market crops with a high-value influence organic farmers' management decisions, particularly regarding the prioritisation of diversity in the cropping systems for agroecological purposes. The farming systems have therefore not undergone major changes of their cropping patterns. Furthermore, there was a general heavy reliance upon input substitution for pest and soil fertility management. This study thus presents new data and a novel analysis of the implications at the farm scale of the global expansion of organic agriculture, and the influence of conventionalisation on farmers practices. [ABSTRACT FROM AUTHOR]

The need for enhancing food production and availability in underprivileged regions of the world requires the attention of scientists. This article explores the possibilities for rethinking agricultural research for development (R4D) in the light of new challenges characterized by a high degree of scientific uncertainty along with associated intense political differences of interest. New challenges that particularly influence food production in underprivileged regions include global climate change, globalization of food chains, and emerging low-carbon energy systems. We argue that by applying the people-centered sustainable livelihoods approach as a research paradigm in R4D, researchers may be more successful in producing knowledge that is useful to entrepreneurial smallholder farmers. Without such rethinking, traditional scientific approaches and logic may limit the contribution that agricultural R4D can make toward the achievement of the Millennium Development Goals of halving extreme hunger by 2015 and improving the livelihoods of all. [ABSTRACT FROM AUTHOR]

Based on three case studies in China and Brazil, this paper explores the terms of access for farmers' participation in certified organic agriculture (OA) and investigates the influence of adoption on productivity, nutrient budgets, income and labour use. Small-scale farmers converting to OA require substantial external production-related, marketing and certification support. Access to OA was strongly dependent upon the type of support available to farmers. Organization based on a contract-farming model resulted in OA only being an option available to a narrow group of farmers, whilst OA initiated by a farmer cooperative provided better access. Gross output was significantly higher for oranges, whilst for the other crops gross output was similar. However, organic farmers in China felt that adoption had improved prices, incomes and market access. Farmers' perception of improved incomes is probably due to improved market access coupled with either a large production base, production intensification and production diversification. This study demonstrates that organization of farmers, and the manner in which this is structured, is crucial for external support to have an effect. Thus, OA may be a development path for small farmers if the supporting structures are provided at a small financial interest rate. [Copyright &y& Elsevier]

Climate-smart approaches have gained momentum in tropical, agricultural development. However, to date, few studies have examined whole-farm greenhouse gas (GHG) balances in smallholder crop-livestock systems. This study aimed to quantify GHG balances at farm-scale, identify GHG hotspots and assess mitigation options in coffee-dairy farms undergoing agricultural intensification in Central Kenya. In recent decades, decreasing farm size has forced the shift from extensive practices to zero-grazing systems and higher nitrogen (N) inputs. We hypothesised that different farm strategies and intensification levels determine the farm’s GHG balance. A farm typology was constructed through principal component analysis (PCA) and hierarchical clustering from 125 farms surveyed. Four farm types were identified ranging relatively from small to large farms, low to high livestock intensities, and low to high N input rates. Whole-farm GHG balances were estimated using an adapted version of the Cool Farm Tool (CFT). Farms were found to be net sources of GHG, averaging from 4.5 t CO 2 eq ha −1 yr −1 in less intensive farms to 12.5 t CO 2 eq ha −1 yr −1 in high intensive farms. Within the farm GHG hotspots identified, methane (CH 4 ) from enteric fermentation processes accounted for 26–39% of total farm GHG emissions; nitrous oxide (N 2 O) and CH 4 from manure management systems (MMS) for 26–38%; soil background and fertilizer induced N 2 O emissions for 24–29%; off-farm production of feeds and agrochemicals for 10–22%; and crop residue management (CRM) for the remaining 1–3%. Within the mitigation practices assessed, zero-grazing stalls already lowered the livestock maintenance energy requirements, reducing enteric fermentation emissions. Stall-feeding, however, brings the necessity-opportunity to manage the manure and our results showed that MMS can be a determining factor in the GHG balance. Increasing the frequency of manure collection from stalls in favour of solid storage systems can reduce N 2 O emissions by up to 75%. Furthermore, dry manure storage reduced the CH 4 emissions of liquid slurry systems by more than 70%. Further benefits in terms of carbon (C) sequestration were identified along farm types from manure and crop residues applications in soils (with averages of −1.3 to −2.3 t CO 2 eq ha −1 yr −1 ) and biomass growth in agroforestry systems (−1.2 to −2 t CO 2 eq ha −1 yr −1 ). Together, soils and woody biomass offset 25–36% of farm emissions. We conclude that reduced farm size and increased livestock density lead to higher emissions per unit area, though this increase is smoothed by larger negative fluxes in soils (by higher C inputs) and woody biomass (by higher tree densities) until a steady state is reached. Average yield-scaled emissions, or product carbon footprints (CFs), resulted in 1.08 kg CO 2 eq kg coffee berry −1 , 0.64 kg CO 2 eq kg maize −1 and 1.05 kg CO 2 eq kg milk −1 on average. CFs did not always differ between farm types and intensification levels, meaning that increases in productivity were not higher than increases in GHG fluxes from intensification. This may be due to: 1) increases in productivity are the result of more processes other than N inputs; and/or 2) emissions from N inputs are overestimated by EFs and GHG calculators. Smallholders may benefit in the near future from climate initiatives and further field characterisation, models calibration and monitoring are required to overcome critical levels of uncertainty and provide more accurate estimations of GHG balances at farm-scale. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) is believed to play a crucial role for many soil functions and ecosystem services. Despite much research, a lower threshold of SOC for sustainable crop production has not been identified across soil types. We addressed a comprehensive dataset with yields of winter wheat for nearly a 1000 field nitrogen (N) response experiments performed over 3 decades in Denmark. The soils ranged from coarse sand to clay loam (0.016-0.406 kg clay kg-1 minerals) with SOC ranging from 0.005 to 0.039 kg kg-1 minerals. All experiments were located on arable soil that was fully fertilized with all other plant nutrients. Based on the yield response at 4-6 levels of applied mineral N, we estimated the potential yield not restricted by any nutrient, Ypot, the yield at no applied N, YN0, the marginal agronomic efficiency (AEN0) in terms of the increase in yield per unit of applied N at zero N, and the level of mineral N, Nopt, needed to obtain Ypot. YN0 increased with Fines20 (proportion of soil minerals < 20 μm). AEN0 decreased with SOC independent of soil type. Nopt decreased with increase in SOC. Ypot increased significantly with a squared expression of Fines20 and decreased significantly with SOC. Ypot was better explained by RH = Fines20/SOC than SOC per se. Our results indicate a positive effect of SOC in terms of a reduction of mineral N needed to obtain the potential crop yield, and a negative effect on Ypot. We suggest a multigate regulation concept for future studies addressing the non-N effect of SOC. We further draw attention to the importance of the quality of the SOC for better understanding effects on crop yields. [ABSTRACT FROM AUTHOR]

Efforts have been made in recent years to improve knowledge about soil greenhouse gas (GHG) fluxes from sub-Saharan Africa. However, data on soil GHG emissions from smallholder coffee-dairy systems have not hitherto been measured experimentally. This study aimed to quantify soil GHG emissions at different spatial and temporal scales in smallholder coffee-dairy farms in Murang'a County, Central Kenya. GHG measurements were carried out for one year, comprising two cropping seasons, using vented static chambers and gas chromatography. Sixty rectangular frames were installed on two farms comprising the three main cropping systems found in the area: 1) coffee ( Coffea arabica L.); 2) Napier grass ( Pennisetum purpureum ); and 3) maize intercropped with beans ( Zea mays and Phaseolus vulgaris ). Within these fields, chambers were allocated on fertilised and unfertilised locations to capture spatial variability. Cumulative annual fluxes in coffee plots ranged from 1 to 1.9 kg N 2 O-N ha − 1 , 6.5 to 7.6 Mg CO 2 -C ha − 1 and − 3.4 to − 2.2 kg CH 4 -C ha − 1 , with 66% to 94% of annual GHG fluxes occurring during rainy seasons. Across the farm plots, coffee received most of the N inputs and had 56% to 89% higher emissions of N 2 O than Napier grass, maize and beans. Within farm plots, two to six times higher emissions were found in fertilised hotspots – around the perimeter of coffee trees or within planted maize rows – than in unfertilised locations between trees, rows and planting holes. Background and induced soil N 2 O emissions from fertiliser and manure applications in the three cropping systems were lower than hypothesized from previous studies and empirical models. This study supplements methods and underlying data for the quantification of GHG emissions at multiple spatial and temporal scales in tropical, smallholder farming systems. Advances towards overcoming the dearth of data will facilitate the understanding of synergies and tradeoffs of climate-smart approaches for low emissions development. [ABSTRACT FROM AUTHOR]

Abstract: Crop-based biofuels represent an environmental and political alternative to fossil fuels, as well as an important source of rural development income; as global biofuel markets continue to mature, however, their impact on food security remains controversial. This study investigates the effects of biofuel feedstock adoption by smallholders in the northwestern Cambodian province of Banteay Meanchey, a region undergoing rapid land use change following the formal end of the Khmer Rouge era in 1989 and subsequent rural resettlement. Remote sensing data combined with field interviews pointed to three discrete phases of land use change in this period: first, as a result of the establishment of new settlements (mainly subsistence rice production); second, via the expansion of cash crop cultivation into forested areas (mainly grown on upland fields); and third, due to the response of smallholders to a sharp increase in regional demand for cassava starch (grown exclusively on upland fields). The study found that agricultural expansion due to cassava growing was severe, but it was not the sole contributor to deforestation in the region. The exposure of smallholder economies to the volatile cassava market had severe consequences for livelihoods and food security. The paper concludes with a discussion of the probable impacts of the emerging cassava market on trajectories in land use, land ownership, and land access in rural Cambodia. The case looks at biofuel adoption in the context of other land use changes, but also provides evidence at the local scale of how a strongly market driven crop, in this case biofuel feedstock, can have striking environmental and socioeconomic consequences. [Copyright &y& Elsevier]