Agronomy for Sustainable Development最新文献

As a fundamental pillar of food security in sub-Saharan Africa (SSA), ensuring seed security is critical to empowering farmers in cultivating food and livestock feed, thereby fostering income generation from agricultural outputs. Among the crops cultivated by smallholders, legumes have the potential to deliver multifaceted benefits. Legumes are nutrient-dense and enhance soil health through their nitrogen-fixing qualities. However, in many instances, the development, release, and supply of improved legume varieties are insufficient to meet the needs of smallholder farmers in SSA. Here, we systematically reviewed the literature to (i) identify and categorize existing legume seed systems, (ii) map legume varieties available to smallholders, (iii) identify barriers hindering the adoption of various legume varieties, and (iv) identify potential strategies and opportunities for strengthening legume seed systems in SSA. Our results demonstrate the coexistence of formal and informal seed systems within legume seed supply chains in SSA, each employing unique seed distribution channels. Smallholders, however, are shown to predominantly depend on the informal seed system to source most legume seeds except for commercially available varieties. We also identified a diverse range of legume varieties available to smallholders in the region, with farmers having varying trait preferences based on crop type and gender. Notably, high yield and abiotic stress tolerance were the most preferred traits. The adoption of these varieties, however, is influenced by various factors, including lack of timely access to seeds in adequate quantities from the formal seed system, high seed costs, and limited information on new varieties. The reviewed literature highlighted that utilizing improved legume varieties had a positive effect on smallholders, leading to improved welfare, food security, dietary diversity, and income. We conclude that the effective scaling of legume systems in SSA is contingent upon the presence of supportive policy frameworks and well-established technical support structures.

Graphical Abstract

Packets of legume seeds within a legume germplasm and breeding program at the University of Zambia (Photo by Caitlin Breen, 2022).

Fruit tree–based agroforestry has been promoted as an alternative farming practice in upland Northwest Vietnam to replace monocultures of staple crops. Although many studies have focused on evaluating the performance of agroforestry systems at the plot level, research on how farmers perceive and evaluate agroforestry considering whole-farm contexts is limited. We explored the perceptions and reasoned management decisions of agroforestry farmers to uncover challenges that hinder the wider use of agroforestry, and we assessed farmers’ strategies for effective management of adoption challenges. We combined the Q methodology and the systems thinking approach. With the Q methodology, we explored prevalent discourses among the members of the farming community on the impact of agroforestry. Systems thinking elucidated a system-wide understanding of farmers’ adaptive decision-making processes. By combining the two approaches, we uncovered the dynamics that shape farmers’ perceptions and the rationale behind their management of the adoption process. Through the Q method, we identified three distinct discourses among participants. Two of these discourses are in favor of agroforestry, highlighting its beneficial impacts on livelihoods and the environment, e.g., through diversification of household income and through soil erosion control. We also generated a collective development pathway outlining how farmers navigated and adapted agroforestry practices to overcome adoption challenges through a whole-system approach to farm resource management. We identified structural barriers, such as unstable farm-gate prices, that may need high-level interventions. Our study adds a new dimension to the assessment of agroforestry through farmers’ perspectives and contributes to the existing body of research on knowledge systems in agroforestry. Considering farmers’ views and their ways of reasoning during innovation processes may allow tailoring appropriate innovations by accounting for unique farm situations and local farming systems. Such locally generated knowledge will have relevance for real-world contexts and therefore be useful for guiding actions.

Agroecology is identified as an important solution to increase the sustainability of agricultural and food systems. Despite the increasing number of publications assessing the socio-economic outcomes of agroecology, very few studies have consolidated the scattered results obtained on various case studies. This paper provides new insights by consolidating evidence on the varied socio-economic effects of agroecology across a large number of cases at a global level. To this purpose, we used a rapid review methodology, screening more than 13,000 publications to retrieve evidence on the socio-economic outcomes of the implementation of agroecological practices. The results of the review indicate that (1) agroecological practices are associated more often with positive socio-economic outcomes across the broad range of evaluated metrics (51% positive, 30% negative, 10% neutral, and 9% inconclusive outcomes); (2) the socio-economic metrics associated with financial capital represent the vast majority of evaluated metrics (83% of total) and are affected positively in a large share of cases (53%), due to favourable outcomes on income, revenues, productivity and efficiency; (3) human capital metrics (16%) are associated with a larger number of negative outcomes (46% versus 38% positive), due to higher labour requirements and costs that are however partly compensated by an overall greater number of positive outcomes on labour productivity (55%); and (4) the results vary depending on the agroecological practice assessed; e.g. for agroforestry, we identify 53% positive outcomes while for cropping system diversification 35%. These results indicate an overall favourable potential for farms to benefit from a positive socio-economic performance with the use of agroecological practices. Yet, the magnitude, temporal aspects, and success factors related to these outcomes, as well as the trade-offs between them, and the system-level effects of an agroecological transition are to be further assessed, since they can have an important influence on the performance of individual farms.

The application of nitrogen (N) fertilizer both underpins high productivity of agricultural systems and contributes to multiple environmental harms. The search for ways that farmers can optimize the N fertilizer applications to their crops is of global significance. A common concept in developing recommendations for N fertilizer applications is the “mass balance paradigm” – that is, bigger crops need more N, and smaller less – despite several studies showing that the crop yield at the optimum N rate (N_opt) is poorly related to N_opt. In this study we simulated two contrasting field experiments where crops were grown for 5 and 16 consecutive years under uniform management, but in which yield at N_opt was poorly correlated to N_opt. We found that N lost to the environment relative to yields (i.e., kg N t^-1) varied +/- 124 and 164 % of the mean in the simulations of the experiments. Conversely, N exported in harvested produce (kg N t^-1) was +/- 11 and 48 % of the mean. Given the experiments were uniformly managed across time, the variations result from crop-to-crop climatic differences. These results provide, for the first time, a quantitative example of the importance of climatic causes of the poor correlation between yield at N_opt and N_opt. An implication of this result is that, even if yield of the coming crop could be accurately predicted it would be of little use in determining the amount of N fertilizer farmers need to apply because of the variability in environmental N losses and/or crop N uptake. These results, in addition to previous empirical evidence that yield at N_opt and N_opt are poorly correlated, may help industry and farmers move to more credible systems of N fertilizer management.

Plant diversification contributes to the ecological intensification of agroecosystems through pest biocontrol services provision. However, the existing evidence for the effectiveness of plant diversification in enhancing pest biocontrol services is highly uncertain across features of plant diversity and biodiversity characteristics. We undertook a comparative meta-analysis focusing on three essential crops (wheat, maize, and soybean) to investigate how diversification schemes in-field (intercropping) and Agri-environmental scheme (AES) around the field (flower strip, hedgerow and field margin) affect arthropod abundance. A random effects analysis was used to determine the role of 10 key factors underlying the effectiveness of plant diversification including biodiversity level and habitat, main and companion plant species, intercropping arrangement, the growth stage of the main crops, type of AES planting scheme, AES planting width, distance from AES plantings and geographical latitude. The overall results revealed that intercropping reduced herbivore and boosted predators and parasitoids abundance significantly, while AES successfully increased predators but not herbivores. Maize intercropping with legume and non-legume plants and row intercropping allowed for effective pest management. The abundance of predators increased in wheat fields immediately adjacent to planting around the field (AES), but this effect declined beyond 5 m from the flower strips. Our results suggest that the response of arthropod abundance to plant diversification is a compromise between spatial management scale, ecological characteristics of arthropod and plant diversification features. These results offer promising pathways for optimizing plant diversification schemes that include functional farm biodiversity across spatial and temporal scales and designing multi-functional landscapes.

Sustainable intensification (SI) responds to the concurrent challenges of increasing food production while reducing the environmental impacts of agriculture. As an early disclosure of innovation, patents are a useful indicator of technology market potential. However, we lack understanding of the extent to which current agricultural technology patents relate to the goals of SI and which kinds of technologies can potentially address SI. Here, we analyzed the diffusion and focus of more than one million patents issued during the period 1970–2022. We explored the degree to which the patents relate to SI through the co-occurrence of efficiency and environmental friendliness targets. Our results reveal that while the rate of patent issuance has dramatically increased over the past five decades, the rate at which patents diffused to different countries had decreased over time. The USA was the biggest net exporter of patents and had produced by far the most high-impact patents (in the top 1% most-cited patents). Since 1970, only 4% of agricultural patents and 6% of high-impact patents were related to SI targets (i.e., promoting both agricultural efficiency and environmental friendliness), but the attention to SI has increased over time. The most highly cited SI-related patents had become more diverse over time, shifting from digital, machine, and energy technologies in 1980s to the current era of agroecology, information, and computer networking. Our results provide an early indication of promising technologies that may play a greater role for SI in the future, subject to the challenges of market transfer and farm adoption and complemented by non-technological innovations in farm management and institutional support.

Perennial cropping systems begin their cycles with a pluriannual immature period. Appropriate management, including the inter-rows, is essential for the long-term viability, and productivity of the plantation while reducing the length of the unproductive period. Despite its significant economic and environmental impacts, the immature period is still poorly characterized and rarely included in the assessment of perennial cropping systems sustainability. Rubber plantations are an interesting case, as a major perennial system in the tropics. Here we conducted a systematic review to identify (1) management practices in inter-rows of immature rubber plantations; (2) the variables used in the literature to analyze the adoption drivers of these practices and to assess their effects on plantation functionalities and performances; and (3) the main effects of diversification practices on plantation functionalities and performances. The major results showed that (1) different inter-row management practices, including a diversity of crops, are possible during the immature period; (2) adoption of diversification practices is driven by few global factors but mostly depends on the specific socio-economic and agroecological context; (3) diversification practices are usually assessed with respect to agronomic and economic performances, and their impacts are generally positive. We identified missing knowledge required for a comprehensive view on current inter-row management practices in immature rubber plantations. First, technical operations should be included in the characterization and assessment of inter-row management practices. Second, a multicriteria assessment framework is required to cover all the sustainability dimensions to guarantee the diffusion of more performant management practices. In order to include the diversity of perceptions of sustainability in rubber plantations, this multicriteria assessment should be based on relevant criteria that combine farmers’ and scientists’ points of view. Detailed characterization of current immature rubber plantations merged with multicriteria assessment will be essential for the design of more sustainable rubber tree cropping systems.

Pesticides threaten biodiversity, but we know little about how they permeate food webs. Few studies have investigated the number, concentration, and composition of pesticides in agroecosystem food webs even though agroecosystems cover one-third of Earth’s land area. We conducted a pioneering study on the distribution of pesticides across local (i.e., on farm) and meta food webs (i.e., regional pool of local food webs) within both perennial (N = 8) and annual crops (N = 11), examining four trophic groups—soil (primary resource), plants (primary producers), rodents (herbivores), and spiders (predators)—for the presence of multiple residues, and comparing these findings to pesticides applied by farmers in recent years. We also undertook interviews with farmers to obtain the most precise information about pesticide applications in their fields. We detected a wide spectrum of pesticides in both annual and perennial crop types. Pesticides applied by farmers represented only a small proportion of all detected pesticides, indicating that pesticides entered local food webs from surrounding landscapes. Some detected pesticides had been banned by the European Union several years ago, which is highly alarming. Trophic group mobility and crop type drove pesticides number at local scale, as mobile groups contained larger numbers of pesticides (probably from encountering wider spectra of pesticides). At a meta scale, spiders contained the highest number of detected pesticides in perennial crops but lowest diversity in annual crops. This might be explained by how spiders’ functional traits are selected in different crops. Insecticides and fungicides concentrations mostly increased with trophic level, indicating bioaccumulation. Herbicides concentration were highest in plants suggesting (bio)degradation. As bioaccumulation outweighed (bio)degradation, pesticides increased overall with trophic level. Therefore, the distribution of pesticides in agroecosystem food webs was affected simultaneously by several mechanisms and depended upon trophic group, crop type, and, probably, surrounding landscape.

There has been substantial research on shade in cacao agroforestry systems, with most studies focusing on the impact of the shade cast by the associated shade trees on microclimate and yield. However, to our knowledge, no cacao agroforestry studies have explored how shade and its microclimate-modifying capacity influence the agrosystem’s pest and disease regulating service. Utilizing thermal hygrometers and hemispherical photographs, we measured temperature and relative humidity during the dry and wet seasons as well as the shade of associated trees (associated shade), combining the latter with cacao self-shade (total shade). This approach enabled us to uncover how each shade type influences microclimate, yields, and pests and diseases beneath cacao trees. Additionally, we developed a novel method to estimate attainable yield, actual yield, and yield loss due to pests and diseases. Using yield loss as a proxy of the pest and disease regulating service and structural equation modeling, we built a model depicting the interaction network between shade types and their role in cacao pest and disease regulation. Our results showed that each shade type uniquely influenced cacao agroecosystem outcomes, with the associated shade negatively impacting attainable yield and total shade having a positive effect. Associated shade also mitigated the dry season microclimate and limited pest and disease occurrence. Notably, shade alone was not the sole pest and disease-related yield loss driver; it is part of a complex interaction network. These innovative shade measurement and yield loss estimation methods have enhanced enhance our understanding of pest and disease regulation. Conclusively, different management approaches for associated shade and total shade are crucial for optimizing yields and pest and disease regulation in cacao agroforestry systems.