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The European Commission recently set a target of increasing the area of organic agriculture to 25% by 2030. To achieve this, it is imperative to understand current nutrient use patterns and identify sustainable nutrient supply opportunities. To that end, this study assessed the sustainability of the current nutrient origin and supply of 71 arable organic farms in 8 European regions. Deficient nutrient supply was found on 24%, 66%, and 56% of farms for nitrogen, phosphorus, and potassium, respectively. On average, we show a moderate surplus for nitrogen (28 kg ha−1), while phosphorus and potassium balances were close to zero (− 1 and 2 kg ha−1, respectively). Large variation between countries and farm types shows a divide between more intensive systems relying on external inputs, and less intensive systems facing nutrient deficits and lower outputs. We show, for the first time, the extent of current use of external input types, where conventional manures supplied 17–26% of external nutrients and inputs from non-agricultural origin supplied 31–41%. A large proportion of nutrient sources within the last group are materials derived from urban wastes. The sustainable expansion of the organic sector will require increased use of locally available recycled fertilizers from urban wastes, and acceptance of such sources by organic farmers is shown to be high, provided they are considered safe.

The increasing resource and ecological challenges in agriculture necessitate agricultural intensification and resource optimization. This study focuses on agroecological intensification using organic practices. It compares the production efficiency of the organic and non-organic smallholder kale production systems in Kenya. Using survey data collected from Kenya, the study estimated production (cost and revenue) efficiency of the kale production system by conducting data envelopment and stochastic frontier analysis and subjected the efficiency measures to propensity score matching analysis. The results show no significant difference in cost efficiency between organic and non-organic kale producers. However, revenue efficiency and income per unit production cost are lower among organic than non-organic kale producers. The results also show that the efficiency and productivity of the organic smallholder kale production system are limited by a lack of inputs (especially manure) but not labor. This implies that improving the efficiency of the smallholder organic kale production system requires more use of organic manure as well as research and training on organic pesticides. The finding concurs with literature that reports organic input problems and lower productivity in organic than non-organic production systems in developing countries and Kenya, especially in vegetables. It also shows that the organic production system is more labor-intensive than the non-organic system.

Organic agriculture uses contracts and networks to overcome its asset‐specificity problems and to ensure compliance with its standards and norms, including environmental conservation. This study analyzed the effects of certified‐organic production on supplier failures and the potential income effects of these failures on vegetable and macadamia producers in Kenya. Using survey data and propensity score matching, the study found that organic macadamia production reduces delivery failures because its asset specificity necessitates a dedicated transport system. It also found that organic vegetable production reduces quality failures because organic consumers are often less concerned about the physical quality of organic produce. However, despite these advantages, cases of supplier failures are still rampant among both organic and nonorganic producers of macadamia and vegetables. The potential income effects of these supplier failures, especially quantity and delivery failures in macadamia, raise concerns. These problems necessitate policy interventions, especially with respect to establishing and strengthening producer organizations, which are often very instrumental in overcoming quality, quantity, and delivery failures.

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.

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 N2O-N ha− 1, 6.5 to 7.6 Mg CO2-C ha− 1 and − 3.4 to − 2.2 kg CH4 -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 N2O 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 N2O 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 wil

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., 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.

Agriculture is one of the major sources of nitrous oxide (N2O), a potent greenhouse gas (GHG) whose atmospheric concentrations are estimated to increase with efforts to increase food production through increasing nitrogen (N) inputs. The objective of this study was to quantify N2O emissions from maize (Zea mays L.) and winter wheat (Triticum aestivum L.) fields amended with inorganic, organic N and a combination of both sources (integrated management), in tropical (Zimbabwe) and temperate (China) climatic conditions. In Zimbabwe N2O emissions were measured from maize plots, while in China emissions were measured from maize and winter wheat plots. In Zimbabwe the treatments were; (i) Control, (ii) 60 kg N ha−1 ammonium nitrate (NH4NO3), (iii) 120 kg N ha−1 NH4NO3, (iv) 60 kg ha−1 cattle (Bos primigenius) manure-N, plus 60 kg N ha−1 NH4NO3, (v) 60 kg N ha−1 cattle manure-N, and (vi) 120 kg N ha−1 cattle manure-N. In China, treatments were; (i) Control, (ii) 300 kg N ha−1 Urea, (iii) 92 kg N ha−1 Urea plus 65 kg ha−1 chicken (Gallus domesticus) manure-N, (iv) 100 kg N ha−1 Urea and (v) 100 kg N ha−1 control release Urea. Our results showed that under both temperate and tropical conditions, integrated nutrient management resulted in lower N2O emissions compared to inorganic fertilizers which had higher total and yield-scale N2O emissions. We conclude that by combining organic and inorganic N sources, smallholder farmers in both China and Zimbabwe, and other countries with similar climatic conditions, can mitigate agricultural emissions without compromising productivity.

Demand for tools to rapidly assess greenhouse gas impacts from policy and technological change in the agricultural sector has catalyzed the development of 'GHG calculators'- simple accounting approaches that use a mix of emission factors and empirical models to calculate GHG emissions with minimal input data. GHG calculators, however, rely on models calibrated from measurements conducted overwhelmingly under temperate, developed country conditions. Here we show that GHG calculators may poorly estimate emissions in tropical developing countries by comparing calculator predictions against measurements from Africa, Asia, and Latin America. Estimates based on GHG calculators were greater than measurements in 70% of the cases, exceeding twice the measured flux nearly half the time. For 41% of the comparisons, calculators incorrectly predicted whether emissions would increase or decrease with a change in management. These results raise concerns about applying GHG calculators to tropical farming systems and emphasize the need to broaden the scope of the underlying data.

To avoid the risks of conventionalisation and becoming a modified version of conventional farming, organic farming is under a continuous pressure to reinvent itself by adopting new technologies. This article examines the role of precaution in organic farmers’ assessment of potential new technologies, and how farmer’s assessment draws on different types of knowledge. The article further explores how knowledge type compares to the role of knowledge and precaution set forth in the principles of organic farming by the organic movement (IFOAM). Results from a case study of the introduction of sewage sludge as an alternative – and controversial - source of nutrients in organic agriculture are presented. Empirically, this case study builds on the analysis of five focus groups with Danish organic farmers. While some farmers called for precaution often backed by an observation of lacking knowledge, others trusted the authorities and accepted sewage sludge, provided it is approved for organic use by the authorities. Our analysis suggests that there is a mismatch between the kind of knowledge used by organic farmers when assessing the new technology, drawing heavily on scientific knowledge, and IFOAMs principles, also hailing experiential knowledge.

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