Agronomy for Sustainable Development最新文献

In Western Africa, agro-sylvo-pastoral systems are dominant and food demand is booming. To meet this demand, many farmers intensify the production with industrial inputs (mineral fertilizers, feeds, pesticides, herbicides). However, the price of these inputs is rocketing. To face this issue, some farmers reconsider crops, livestock, and tree synergies and by-product recycling to increase their production sustainably at a lower cost. The study aimed to characterize the diversity of Koumbia’s farming systems and to assess farming systems’ technical performance in an agroecological perspective. We surveyed 391 farms in the county of Koumbia (Burkina Faso). Considering 15 agricultural practices (4 on by-products recycling, 4 on soil protection, 4 on industrial inputs limitation, 2 on smart use of natural resources, and 1 on cropping diversification), a multivariate analysis (PCA+HAC) combined to an agroecology (Ae) scoring system (−15 to +15) based on 15 specific indicators (one/practice), we highlighted 3 agroecological farming systems clusters. These clusters are distributed along a gradient of agroecology intensity (Ae+: high degree of Ae, Ae+/−: medium degree, and Ae−: poor degree). Ae+ farms (Ae score: +3.0) group 17% of the farms, Ae+/− (Ae score: −4.5) group 58% of the farms, and Ae− (Ae score: −10.5) group 25% of the farms. Ae+ raise more livestock and recycle a higher rate of crop-livestock by-products in fodder, organic manure, and mulch. These recycling practices are facilitated by better levels of equipment for transportation and storage and soil water and crop residue conservation measures, including maintenance of the wooded park on the cultivated fields. This set of practices, which close better the agricultural system, produces a systemic effect which has a positive impact on yields and on the whole ecosystem. Our findings outline for the first time that crop-livestock synergies and by-product recycling are major factors of agroecological transition in agro-sylvo-pastoral systems.

Agriculture can benefit from crop diversification to facilitate its transition to more sustainable agrifood systems. However, these practices remain rare in Europe. One major barrier is the existence of sociotechnical lock-ins. To clarify the dynamics at work, we analyzed the relationships between actors involved in 23 crop diversification experiences across 11 European countries. The novelty of this paper lies in the systemic analysis of the network of actors involved in crop diversification experiences. Using data from qualitative interviews and cognitive mapping approaches, we identify and describe the role of actors and the key relationships in crop diversification and detect relationships that are currently missing. Our study shows that in the different European countries, similar relationships act as levers or barriers to crop diversification, with farmers and researchers playing a crucial role. The most important cognitive factors that influence the choice of farmers to diversify are environmental and health concerns and the desire to make profit and innovate. We relate the cognitive factors to organizational, technical, economic, and political factors and suggest levers for crop diversification based on successful crop diversification experiences.

Cover crops (CCs) can affect the cropping systems’ N dynamics and soil water content (SWC), but optimizing their potential effects requires knowledge of their growth pattern, N accumulation, and mineralization. For this purpose, a 3-year field experiment was initiated in northeast Italy involving a maize-soybean rotation. The objectives of this study were to (i) evaluate the use of time series vegetation indices (VIs) obtained from the Sentinel-2 satellite for monitoring the growth of CCs and estimating their biomass and N uptake at termination; (ii) investigate the effects of different CCs on cash crop yield and SWC; and (iii) use the simulation model CC-NCALC to predict the nitrogen contribution of CCs to subsequent cash crops. Three CC systems were tested: a fixed treatment with triticale; a 3-year succession of rye, crimson clover, and mustard; and a control with no CCs. Satellite imagery revealed that rye and triticale grew faster during the winter season than clover but slower compared to mustard, which suffered a frost winterkilling. Both grasses and mustard produced greater biomass at termination compared to clover, but none of the CC species affected SWC or yield and N uptake of the cash crop. A net N mineralization of all the CC residues was estimated by the model (except for the N immobilization after triticale roots residues). During the subsequent cash crop season, the estimated clover and mustard N released was around 33%, and the triticale around 3% of their total N uptake, with a release peak 2 months after their termination. The use of remote sensing imagery and a prediction model of CC residue decomposition showed potential to be used as instruments for optimizing the CCs utilization and enhancing cropping water and N fertilization management efficiency; however, it must be further analyzed with other CCs species, environmental conditions, and cropping systems.

The decoupling of crop and livestock in space is currently threatening the sustainable development of agriculture. One of the major challenges is to identify the imbalanced space between cropland and livestock farms. This paper proposes a new methodology to identify such areas at the raster scale, without being limited by traditional administrative division restrictions. The method takes into account nutrient flow, economic cost, and spatial distributions of cropland and livestock farms. The methodology was applied to the Heihe River Basin of China as an example. First, we calculated the nutrient demands on croplands and the supply of livestock manure. Second, we proposed a new method to capture the imbalanced space between cropland and livestock farms. The method was improved on the Gaussian two-step floating catchment area (2SFA) method. To our knowledge, this is the first time such a method has been applied in agriculture. Third, we applied the maximum coverage model to select sites for manure transfer hubs in the imbalanced space of cropland and livestock farms. In this way, the distance of transferring manure can be effectively reduced. Our results showed that the total amount of manure nutrients was sufficient to meet the requirements of local crops in over 90% of the counties located within the Basin. Despite the potential benefits of manure as a fertilizer, its adoption could be more expensive than chemical fertilizers on almost 92% of the croplands due to the high transportation costs associated with spatial separation. However, the identification of 119 transfer hub sites significantly enhanced the accessibility of manure for returning to croplands, ultimately resulting in the optimization of 32% of the previously imbalanced spatial relationship between cropland and livestock farms. The method facilitates raster-scale identification of imbalanced space between cropland and livestock farms, with wide applicability across regions globally.

Abstract 

Fruit tree productivity is generally low and highly variable in the tropics. Quantifying yield gaps and their determining factors provides levers to increase production, but yield gap of fruit trees remains poorly explored at the tree scale. In order to bridge this knowledge gap, we adapted the concept of yield gap to define the production gap at the tree scale to integrate tree endogenous factors (cultivar, age, and crown dimensions). The production gap (P_g) was defined as the difference between potential tree production (P_p) and actual tree production (P_a). The concept was implemented for mango trees in West Africa. We estimated these production indicators on 280 mango trees for two years, covering a wide range of fruit load, age, cultivars, and cropping systems (extensive, diversified, and intensive) found in Senegal. Actual production was estimated yearly using ground tree image analysis. Attainable production (P_att, a locally constrained approximation of P_p) was estimated based on tree endogenous and climatic factors using stochastic frontier analysis. Our results showed that attainable production increased with tree crown area and trunk diameter, whereas the effects of tree density, temperature, and solar radiation were cultivar-dependent. On average, the actual production reached 63% of the attainable production. The production gap was higher in extensive orchards (P_g = 58% of P_att) compared to diversified (P_g = 29% of P_att) and intensive (P_g = 32% of P_att) orchards. Based on production gap estimation, we identified the drivers of mango production variation among cultivars and cropping systems in West Africa. This study demonstrates the usefulness of adapting yield gap methodology to the tree scale to analyze production gaps in diverse fruit tree-based cropping systems. Measurement of production gaps allows the integration of tree features and their variability to upscale and improve the estimation of yield gaps at the orchard scale.

Legume inclusion into cropping systems has been proposed to maintain high crop yields while offering multiple environmental benefits. However, the effect of legumes as pre-crop on subsequent wheat yield and soil has not been well explored. Thus, a 7-year field experiment was used to determine the interactive effects of mineral fertilization and legumes (peanut, mung bean, soybean, adzuki bean) inclusion on wheat productivity and soil quality. Our results showed that legume inclusion led to a higher wheat yield advantage (52% on average) than maize–wheat rotation under no fertilization but the advantage decreased to 26% with fertilization. All legume–wheat rotation systems supported stable wheat production, where a stronger effect was observed after peanut than after maize. Meanwhile, the wheat yield under legume–wheat systems was more resistant (i.e., less variability in the yield after ceasing fertilization) and more resilient (i.e., recovering more quickly after fertilizer re-application) relative to maize-wheat. Furthermore, soil ecosystem multifunctionality increased by 0.8 times in the topsoil while maintaining soil organic carbon stocks, even with low C and N inputs under legume–wheat. Interestingly, we also observed a positive correlation between wheat yield and soil ecosystem multifunctionality. In conclusion, legume inclusion as a sustainable practice can optimize crop yields by enhancing soil multifunctionality while maintaining soil organic carbon stocks, particularly for integration into low-yielding agroecosystems.

Soil health metrics with strong links to ecological function and agricultural productivity are needed to ensure that future management of agricultural systems meets sustainability goals. While ecological metrics and crop yields are often considered separately from one another, our work sought to assess the links between the two in an agricultural context where productivity is a key consideration. Here, we investigated the value of soil health tests in terms of their relevance to agricultural management practices and crop yields at contrasting long term cropping systems experiments. One site was on a sandy loam Leptic Podzol and the other on a sandy clay loam Endostagnic Luvisol. Furthermore, the experiments had different management systems. One contained legume-supported rotations with different grass-clover ley durations and organic amendment usage, while the other compared a range of nutrient input options through fertiliser and organic amendments on the same rotation without ley periods. Metrics included field tests (earthworm counts and visual evaluation of soil structure scores) with laboratory analysis of soil structure, chemistry and biology. This analysis included bulk density, macroporosity, pH, available phosphorus, exchangeable potassium, soil organic matter and potentially mineralizable nitrogen. Using a novel combination of long-term experiments, management systems and distinctive soil types, we demonstrated that as well as providing nutrients, agricultural management which resulted in better soil organic matter, pH, potassium and bulk density was correlated with higher crop yields. The importance of ley duration and potentially mineralizable nitrogen to yield in legume-supported systems showed the impact of agricultural management on soil biology. In systems with applications of synthetic fertiliser, earthworm counts and visual evaluation of soil structure scores were correlated with higher yields. We concluded that agricultural management altered yields not just through direct supply of nutrients to crops, but also through the changes in soil health measured by simple metrics.

The growing demand for sustainable agriculture is raising interest in intercropping for its multiple potential benefits to avoid or limit the use of chemical inputs or increase the production per surface unit. Predicting the existence and magnitude of those benefits remains a challenge given the numerous interactions between interspecific plant-plant relationships, their environment, and the agricultural practices. Soil-crop models are critical in understanding these interactions in dynamics during the whole growing season, but few models are capable of accurately simulating intercropping systems. In this study, we propose a set of simple and generic formalisms (i.e. the structure and mathematical representation necessary for designing a model) for simulating key interactions in bi-specific intercropping systems that can be readily included into existing dynamic crop models. This requires simulating important processes such as development, light interception, plant growth, N and water balance, and yield formation in response to management practices, soil conditions, and climate. These formalisms were integrated into the STICS soil-crop model and evaluated using observed data of intercropping systems of cereal and legumes mixtures, including Faba bean-Wheat, Pea-Barley, Soybean-Sunflower, and Wheat-Pea mixtures. We demonstrate that the proposed formalisms provide a comprehensive simulation of soil-plant interactions in various types of bispecific intercrops. The model was found consistent and generic under a range of spring and winter intercrops (nRMSE = 25% for maximum leaf area index, 23% for shoot biomass at harvest, and 18% for grain yield). This is the first time a complete set of formalisms has been developed and published for simulating bi-specific intercropping systems and integrated into a soil-crop model. With its emphasis on being generic, sufficiently accurate, simple, and easy to parameterize, STICS is well-suited to help researchers designing in silico the agroecological transition by virtually pre-screening sustainable, manageable intercrop systems adapted to local conditions.

Agriculture faces potentially competing societal demands to produce food, fiber and fuel while reducing negative environmental impacts and delivering regulating, supporting and cultural ecosystem services. This necessitates a new generation of long-term agricultural field experiments designed to study the behavior of contrasting cropping systems in terms of multiple outcomes. We document the principles and practices of a new long-term experiment of this type at Rothamsted, established at two contrasting sites in 2017 and 2018, and report initial yield data at the crop and system level. The objective of the Large-Scale Rotation Experiment was to establish gradients of system properties and outcomes to improve our fundamental understanding of UK cropping systems. It is composed of four management factors—phased rotations, cultivation (conventional vs reduced tillage), nutrition (additional organic amendment vs standard mineral fertilization) and crop protection (conventional vs smart crop protection). These factors were combined in a balanced design resulting in 24 emergent cropping systems at each site and can be analyzed at the level of the system or component management factors. We observed interactions between management factors and with the environment on crop yields, justifying the systems level, multi-site approach. Reduced tillage resulted in lower wheat yields but the effect varied with rotation, previous-crop and site. Organic amendments significantly increased spring barley yield by 8% on average though the effect again varied with site. The plowed cropping systems tended to produce higher caloric yield overall than systems under reduced tillage. Additional response variables are being monitored to study synergies and trade-offs with outcomes other than yield at the cropping system level. The experiment has been established as a long-term resource for inter-disciplinary research. By documenting the design process, we aim to facilitate the adoption of similar approaches to system-scale agricultural experimentation to inform the transition to more sustainable cropping systems.