Africa SOIL: Soil Organic matter Improves Livelihoods

背景：南部非洲正受到气候变化的严重影响，导致普遍贫困和营养不良。这些影响因人口压力增加、资源（例如养分、水和土壤）有限而加剧，导致产量低且不稳定、土壤逐步退化和土壤有机质等固有土壤资源耗竭。小农系统依赖于退化的低肥力土壤，特别脆弱，导致赤贫。玉米是东部和南部非洲1.6亿多人口最重要的作物，占耕地面积的50-90%（超过1700万公顷，不包括南非），总产量为3100万吨。然而，如果在气候变化和土壤养分供应不足的情况下不采取新的做法，预计已经很低的产量将进一步下降，农民无法摆脱这一贫困陷阱。这些系统迫切需要将可持续作物生产和在不断变化的条件下保护土壤资源结合起来的技术。培育耐旱性更强、从土壤有机质中吸收氮的能力更强的玉米新品种，有望改变这些种植制度。目的和目标：我们的目标是通过赋予小农知识和工具来更有效地补充和利用土壤中的养分，从而为这一问题提供解决方案。具体而言，这将涉及将保护性农业做法与选择最能从土壤有机质中获得氮的玉米品种相结合。这将减少对无机肥料施用的需求和依赖，以提高产量。这提供了生产力和环境效益：在不断变化的条件下，特别是干旱条件下，产量更稳定，降低了对无机肥料投入的需求，并通过改善土壤结构避免土壤进一步退化。首先，我们将通过在津巴布韦东北部和马拉维南部现有的小农农场网络中建立示范和试验点，转化和建立我们现有的关于不同玉米品种从有机物质中获取营养的能力的知识。我们将与农民讨论我们的方法，增加土壤有机质的策略以及在当地环境和土壤条件下对玉米产量的预期影响。现场调查结果将构成对这项技术进行环境和经济评估的基础，并将土壤有机质考虑因素纳入现有的保护性农业准则。最后，我们将与植物育种者合作，努力将环境可持续性标准纳入玉米育种计划。潜在应用和惠益：基于减少土壤逆转、作物残茬保留和多样化的保护性农业最适合在干旱条件下退化的低肥力土壤上实施。一些耐旱的玉米品种是保护性农业中土壤有机质补充的良好利用者，预计将产生经济和环境效益。将此嵌入品种选择标准，使我们走向未来的可持续性育种，最适合南部非洲的当地环境。这是改善粮食和营养安全、环境可持续性、减少贫穷和改善南部非洲小农和农村人口特别是妇女的生产环境的重要一步。

Context:Southern Africa is being severely impacted by climate change, resulting in widespread poverty and under-nutrition. These effects are exacerbated by increasing population pressure, limiting resources (e.g. nutrients, water and soils), resulting in low, unstable yields, progressive soil degradation and depletion of inherent soil resources, such as soil organic matter. Smallholder systems, dependent on degraded soil of low fertility, are particularly vulnerable and lead to abject poverty. Maize is the single most important crop for more than 160 million people in eastern and southern Africa, occupying between 50-90% of the cultivated land area (over 17 million hectares, excluding South Africa), with a total production of 31 million tonnes. However, without new practices in the face of climate change and low soil nutrient availability, yields which are already low are predicted to further decline and farmers cannot escape this poverty trap. Technologies are urgently required for these systems that couple sustainable crop production and protection of the soil resource under changing conditions. Breeding for new maize varieties with greater tolerance to drought and enhanced ability to take up nitrogen from soil organic matter holds much promise to transform these cropping systems. Aims and objectives:Our aim is to provide a solution to this problem by empowering smallholder farmers with the knowledge and tools to replenish and utilise nutrients in soil more efficiently. Specifically, this will involve coupling conservation agriculture practices with selection of maize varieties best able to source nitrogen from soil organic matter. This will reduce the requirement and dependency for inorganic fertiliser application to improve yields. This provides both productivity and environmental benefits: greater yield stability under changing conditions particularly drought, lowering the need for inorganic fertiliser input, and averting further soil degradation through enhancing soil structure. Firstly, we will translate and build on our existing knowledge of abilities of different maize varieties to source nutrients from organic matter through establishment of demonstration and trial sites across an existing network of smallholder farms in NE Zimbabwe and S Malawi. We will discuss with farmers our approach, strategies to increase soil organic matter and expected impacts on maize yield in the context of local environmental and soil conditions. On-site findings will form the basis for environmental and economic assessments of this technology, and for soil organic matter considerations to be embedded into existing guidelines for conservation agriculture. Finally, we will work with plant breeders to move towards integrating environmental sustainability criteria into maize breeding programmes. Potential applications and benefits:Conservation agriculture, based on reduced soil inversion, crop residue retention and diversification is best suited to be practised under degraded, low fertile soils under drought conditions. Some drought tolerant maize varieties are excellent utilisers of soil organic matter replenished during conservation agriculture, which is anticipated to incur both economic and environmental benefits. Embedding this into variety selection criteria, takes us towards future breeding for sustainability that is best suited to the local context in southern Africa. This is an important step for improving food and nutritional security, environmental sustainability, reducing poverty, and enhancing the production environment of smallholder farmers and rural populations, in particular women, in southern Africa.