• Authors:
    • Dequiedt, B.
    • Moran, D.
  • Source: Ecological Economics
  • Volume: 110
  • Year: 2015
  • Summary: This paper considers the cost of greenhouse gas mitigation potential of legume crops in French arable systems. We construct marginal abatement cost curves to represent this mitigation or abatement potential for each department of France and provide a spatial representation of its extent. Despite some uncertainty, the measure appears to offer a significant low cost mitigation potential. We estimate that the measure could abate half of the emission reduction sought by a national plan for the reduction of chemical fertilizer emissions by 2020. This would be achieved at a loss of farmland profit of 1.2%. Considering the geographical heterogeneity of cost, we suggest that a policy implementing carbon pricing in agriculture would be more efficient than a uniform regulatory requirement for including the crop in arable systems.
  • Authors:
    • Cornet,D.
    • Sierra,J.
    • Tournebize,R.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 1
  • Year: 2015
  • Summary: Yams are a neglected crop, grown mostly in West Africa by resource-poor farmers. Little is known about the physiology of the crop, and researchers lack practical and efficient tools to conduct growth analysis. The objective of this study was to develop allometric models able to predict yam leaf area and leaf and stem dry mass with acceptable accuracy. The models were calibrated using a data set comprising 10 cultivars belonging to the two main species ( Dioscorea alata L. and D. rotundata Poir.) grown at two locations in Guadeloupe (Lesser Antilles) and two locations in Benin (West Africa). The best models were selected based on Akaike's information criteria and validated against independent data sets. A power regression was best for predicting leaf area from leaf measurements while linear relationships were sufficient to predict the relationship between crop leaf area and leaf and stem mass. The use of species-specific models for the estimation of leaf and stem mass significantly improved the models' performance. Models predicting yam leaf area and leaf mass proved to be reliable and accurate (no significant deviation and adjusted R2>0.95). For stem mass, overestimation always occurred during validation (9%). To overcome this discrepancy, a methodology was proposed that allows the user to calibrate the model by tailoring the sampling size to obtain the required precision. The use of the selected models provides a nondestructive and reliable alternative to estimate leaf area and leaf and stem biomass for different cultivars and sites.
  • Authors:
    • Nowak,B.
    • Nesme,T.
    • David,C.
    • Pellerin,S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 204
  • Year: 2015
  • Summary: Many authors have focused on the contribution of inner farm nutrient recycling to closed nutrient cycles, but little is known about the contribution of exchanges among farms to nutrient cycling. By using a network approach, we assessed the structure of farm mass flows networks and their consequences for nitrogen (N), phosphorus (P) and potassium (K) recycling in organic farming at the local scale. Organic farming was considered as a prototype of farming systems that aims at better closing nutrient cycles. Inflows and outflows were collected for two cropping years on 63 organic farms. The farms were located in three French agricultural districts with areas ranging from 520 to 1021 km 2 and differentiated by their degree of specialization (specialized in crop production, animal production, or mixed). Local nutrient recycling was assessed at the district scale through: (i) the local supply, defined as the ratio of the amount of nutrients from exchanges among farms plus the amount of nitrogen from atmospheric sources, to the sum of inputs to organic farms; and (ii) the cycling index, defined as the fraction of nutrients flowing at least twice through the same farms. Results showed that exchanges among farms were mainly short-distance exchanges (<50 km on average) and contributed up to 70% of farm nutrient inflow. Mass flows among farms were two to four times greater in the mixed district than in specialized districts. As a consequence, both the local supply and the cycling index were greater in the mixed district than in the specialized districts. However, even if the local supply was generally high (85%, 52% and 54% for N, P and K inflows in the mixed district, respectively), the cycling index remained low (5%, 20% and 10% for N, P and K in the mixed district), indicating that most flows among farms were one-way and not actual nutrient recycling. This study contributes to the understanding of the magnitude, conditions and factors of nutrient recycling in agriculture at the local scale.
  • Authors:
    • Tribouillois,H.
    • Cruz,P.
    • Cohan,J. P.
    • Justes,E.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 207
  • Year: 2015
  • Summary: Cover crops are used during fallow periods to produce ecosystem services, especially those related to N management such as (i) capturing mineral-N from soil to reduce nitrate leaching, and (ii) improving N availability for the next main crop (green manuring). Bispecific mixtures consisting of legume and non-legume species could simultaneously produce these two services of nitrate saving and green manuring. The magnitude of these services can be estimated from indicators of agroecosystem functions such as crop growth rate, crop N acquisition rate and the C:N ratio of the cover crop. We developed a conceptual model for each indicator which was described using general linear models. A three-step procedure was used: (1) represent the behavior of each species based on a sub-model and calibrate each species in bispecific mixtures; (2) validate the complete-mixture models, corresponding to the sum of the two species sub-models, and the proportion of each species in the whole cover, and (3) validate the generality of sub-models and complete-mixture models to predict the agroecosystem function indicators of species in mixture not used for calibration. The combined use of (i) potential agroecosystem functions measured in sole crop in non-limiting conditions, (ii) difference in leaf functional traits, as indicators of plant strategies and (iii) environmental factors, was efficient in fitting and predicting the level of agroecosystem functions provided by a cover crop species in mixture in actual conditions. The models fitted for bispecific mixtures were efficient to represent the behavior of each species in mixture and to estimate the legume proportion which expressed the species dominance. The models were evaluated as satisfactory for crop growth rate and C:N ratio for their generality in predicting the agroecosystem functions provided in mixtures by other species not used in the model calibration step, which illustrates the relevance and robustness of the approach.
  • Authors:
    • Watson,James
    • Challinor,Andrew J.
    • Fricker,Thomas E.
    • Ferro,Christopher A. T.
  • Source: Climatic Change
  • Volume: 132
  • Issue: 1
  • Year: 2015
  • Summary: Understanding the relationship between climate and crop productivity is a key component of projections of future food production, and hence assessments of food security. Climate models and crop yield datasets have errors, but the effects of these errors on regional scale crop models is not well categorized and understood. In this study we compare the effect of synthetic errors in temperature and precipitation observations on the hindcast skill of a process-based crop model and a statistical crop model. We find that errors in temperature data have a significantly stronger influence on both models than errors in precipitation. We also identify key differences in the responses of these models to different types of input data error. Statistical and process-based model responses differ depending on whether synthetic errors are overestimates or underestimates. We also investigate the impact of crop yield calibration data on model skill for both models, using datasets of yield at three different spatial scales. Whilst important for both models, the statistical model is more strongly influenced by crop yield scale than the process-based crop model. However, our results question the value of high resolution yield data for improving the skill of crop models; we find a focus on accuracy to be more likely to be valuable. For both crop models, and for all three spatial scales of yield calibration data, we found that model skill is greatest where growing area is above 10-15 %. Thus information on area harvested would appear to be a priority for data collection efforts. These results are important for three reasons. First, understanding how different crop models rely on different characteristics of temperature, precipitation and crop yield data allows us to match the model type to the available data. Second, we can prioritize where improvements in climate and crop yield data should be directed. Third, as better climate and crop yield data becomes available, we can predict how crop model skill should improve.
  • Authors:
    • Bosco,S.
    • Volpi,I.
    • o Di Nasso,N. N.
    • Triana,F.
    • Roncucci,N.
    • Tozzini,C.
    • Villani,R.
    • Laville,P.
    • Neri,S.
    • Mattei,F.
    • Virgili,G.
    • Nuvoli,S.
    • Fabbrini,L.
    • Bonari,E.
  • Source: Italian Journal of Agronomy
  • Volume: 10
  • Issue: 3
  • Year: 2015
  • Summary: Agricultural activities are co-responsible for the emission of the most important greenhouse gases: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Development of methodologies to improve monitoring techniques for N2O are still needful. The LIFE+IPNOA project aims to improve the emissions monitoring of nitrous oxide from agricultural soils and to identify the agricultural practices that can limit N2O production. In order to achieve this objective, both a mobile and a stationary instrument were developed and validated. Several experimental field trials were set up in two different sites investigating the most representative crops of Tuscany (Central Italy), namely durum wheat, maize, sunflower, tomato and faba bean. The field trials were realized in order to test the effect on N2O emissions of key factors: tillage intensity, nitrogen fertiliser rate and irrigation. The field trial on durum wheat was set up in 2013 to test the effect of tillage intensity (minimum and conventional tillage) and nitrogen fertilisation rate (0, 110, 170 kg N ha-1) on soil N2O flux. Monitoring was carried out using the IPNOA mobile prototype. Preliminary results on N2O emissions for the durum wheat growing season showed that mean daily N2O fluxes ranged from –0.13 to 6.43 mg m-2 day-1 and cumulative N2O-N emissions over the period ranged from 827 to 2340 g N2O-N ha-1. Tillage did not affect N2O flux while increasing nitrogen fertilisation rate resulted to significantly increase N2O emissions. The IPNOA mobile prototype performed well during this first year of monitoring, allowing to catch both very low fluxes and peaks on N2O emissions after nitrogen supply, showing a good suitability to the field conditions. © S. Bosco et al., 2015 Licensee PAGEPress, Italy.
  • Authors:
    • Queiros,J.
    • Malca,J.
    • Freire,F.
  • Source: Journal of Cleaner Production
  • Volume: 99
  • Year: 2015
  • Summary: This article presents a life-cycle assessment (LCA) of rapeseed produced in Central Europe (France, Germany and Poland), addressing different fertilization and management practices. Two alternative fertilization scenarios were compared (on the basis of the most common fertilizer types used in Europe, namely nitrogen, phosphate P 2O 5, and potash K 2O fertilizers) and two different scenarios of soil management practices were assessed (taking into account climate and soil type prevalent in each region). Six environmental impact categories were investigated: abiotic depletion; global warming; acidification; eutrophication; ozone layer depletion; and photochemical oxidation. Results showed that the choice of fertilizer type had significant implications in the environmental impacts. Calcium ammonium nitrate (CAN) manufacturing had considerably higher greenhouse gas emissions than urea production, due to the use of nitric acid in the former. In terms of field emissions, ammonia and nitrate released following the application of nitrogen fertilizers dominated the acidification and eutrophication impacts. Nitrogen-phosphorus-potassium (NPK) compounds showed particularly high impacts in terms of photochemical oxidation, as a result of sulfur dioxide emissions from manufacturing. The remaining fertilizers (P 2O 5 and K 2O) hardly contributed to the impacts. Soil carbon change associated with different agricultural management practices significantly contributed to the greenhouse gas (GHG) intensity of rapeseed production, but important soil carbon stock variations were calculated: between 938 (release) and 271 kg CO 2eq/1000 kg dry seeds (sequestration) due to different standard soil organic carbon contents in the three rapeseed production systems and alternative tillage methods in the reference scenarios of land management.
  • Authors:
    • Monti, A.
    • Fernando, A. L.
    • Schmidt, T.
    • Rettenmaier, N.
  • Source: Research Article
  • Volume: 8
  • Issue: 4
  • Year: 2015
  • Summary: Agricultural systems in the Mediterranean region are increasingly getting under pressure due to both global warming and the aggravating competition for agricultural land. Perennial grasses have the potential to tackle both challenges: they are drought-resistant crops and considered not to compete for high-productivity agricultural land because they can be grown on marginal land. This paper presents the outcome of a screening life cycle assessment (LCA) conducted as part of an integrated sustainability assessment within the EU-funded project ‘Optimization of Perennial Grasses for Biomass Production’ (OPTIMA). The project aims at optimised production of Miscanthus (Miscanthus × giganteus), giant reed (Arundo donax L.), switchgrass (Panicum virgatum L.) and cardoon (Cynara cardunculus L.) on marginal land in the Mediterranean region. Different cultivation and use options were investigated by comparing the entire life cycles of bioenergy and bio-based products to equivalent conventional products. The LCA results show that the cultivation of perennial grasses on marginal land and their use for stationary heat and power generation can achieve substantial greenhouse gas emission and non-renewable energy savings, with Miscanthus allowing for savings ranging up to 13 t CO2 eq./(ha · year) and 230 GJ/(ha · year), respectively. Negative environmental impacts are less pronounced. Significant parameters include irrigation needs and moisture content at harvest, which determines energy demand for technical drying. We conclude that the cultivation of perennial grasses on marginal land in the Mediterranean region provides potentials for climate change mitigation together with comparatively low other environmental impacts, if several boundary conditions and recommendations are met. © 2015, Springer Science+Business Media New York.
  • Authors:
    • Grehan, E.
    • Tournebize, J.
    • Billen, G.
    • Garnier, J.
    • Benoit, M.
    • Bruno, M.
  • Source: Article
  • Volume: 213
  • Year: 2015
  • Summary: Agricultural activities can lead to nitrogen losses in the environment, particularly nitrate (NO 3-) leaching and nitrous oxide (N 2O) emissions. This study aims to measure N losses from organic farming (OF) and conventional farming (CF) arable cropping systems, both adopted in a single farm, located on the same drained loamy soil in the Seine basin, in the North of France. Leaching was measured with ceramic cups and N 2O emissions with automatic and manual chambers over the 2011-2014 period. Manual chambers showed the same trend as automatic chambers but underestimated small variations and overestimated peak emissions. On average, N 2O emissions were lower in OF (0.650.64 kg N ha -1 yr -1) than in CF fields (0.950.77 kg N ha -1 yr -1). The mean amount of N leached was 13.3 kg N ha -1 yr -1 in the OF system during the 8-crops rotation (alfalfa 1, alfalfa 2, wheat, green bean, wheat, faba bean, wheat, flax) and 18.4 kg N ha -1 yr -1 in the CF system for a 3-crops CF rotation (legume, wheat, wheat), corresponding to 9 and 10% of total N inputs, respectively. Leached N and N 2O emissions expressed per unit of protein-N harvested were slightly higher in CF (0.11 kg NO 3-N kg -1 N yr -1 and 5.4 N 2O-N kg -1 N yr -1, respectively) than in OF systems (0.10 kg NO 3-N kg -1 N yr -1 and 4.7 g N 2O-N kg -1 N yr -1, respectively). These results show a relative lower environmental impact of OF practices compared to CF practices (-30% area-scaled and -12% yield-scaled for leaching and N 2O emissions), with further margins of progress in both systems, including a better management of fertilisers, legumes and catch-crops.
  • Authors:
    • Colnenne-David,Caroline
    • Dore,Thierry
  • Source: Renewable Agriculture and Food Systems
  • Volume: 30
  • Issue: 6
  • Year: 2015
  • Summary: Agriculture must face a number of very pressing environmental issues. We used the prototyping method to design three innovative cropping systems, each satisfying three ambitious goals simultaneously: (1) overcoming a major environmental constraint, which represents a major break regarding objectives to be reached in current cropping systems (differing between systems: a ban on all pesticides but with chemical nitrogen (N) fertilizer permitted; reducing fossil energy consumption by 50%; or decreasing greenhouse gas (GHG) emissions by 50%), (2) meeting a wide range of environmental criteria and (3) maximizing yields, given the major constraint and environmental targets. A fourth cropping system was designed, in which the environmental and yield targets were achieved with no major constraint (the productive high environmental performance cropping system (PHEP) system). The performances of these innovative cropping systems were compared to a conventional system in the Ile-de-France region. We used a three-step prototyping method: (1) new cropping systems were designed on the basis of scientific and expert knowledge, (2) these system prototypes were assessed with tools and a model (ex ante assessment) adjusted to the set of constraints and targets, with optimization by an iterative process until the criteria were satisfied and (3) evaluation in a long-term field experiment (ex post assessment), which is currently underway. We describe only the first two steps here, together with the results of the prototypes assessment with tools and a model. The pesticide, energy and GHG constraints were fulfilled. All these innovative systems satisfied environmental criteria in terms of nitrogen and phosphorus management, pesticide use, energy consumption and crop diversity. For the pesticide-free system, the soil organic matter indicator was lower than expected due to frequent plowing (every 2 years) and yields were 20-50% lower than for the PHEP system, depending on the crop considered. We focus our discussions on the design methodology and the availability of scientific knowledge and tools for projects of this type.