Conservation agriculture (CA) is increasingly promoted among smallholder farmers of sub-Saharan Africa in a quest to improve food security while sustaining the natural resource base of the agro-ecosystems where agriculture is based. The aim of this study was to investigate the effects of CA and traditional tillage on soil organic carbon (SOC) and selected hydraulic properties in two contrasting agro-ecological zones of Malawi. Six farmers hosted on-farm trials in each location, with each farmer having the following treatments: CA with continuous sole maize (CA-SM), CA with maize–legume intercrops (CA-ML), and traditional tillage with continuous sole maize (CT-SM). Soil samples were randomly collected in October 2015, from farmers’ fields located in Chipeni, Chinguluwe, Lemu, and Zidyana where CA had been implemented for 10 years (2005–2015) at six depth intervals: 0–10, 10–20, 20–40, 40–60, 60–80, and 80–100 cm. Bulk density, soil water characteristics, and pore size distribution were determined using undisturbed core samples. At all sites, CA improved total SOC, carbon stocks, and the stable fraction of particulate organic carbon. Maize–legume intercropping under CA had 35%, 33%, and 73% more total SOC than CT-SM in Chipeni, Lemu, and Zidyana respectively. In Chinguluwe and Lemu, CA-ML had 0.54 and 0.50 g kg–1 respectively more stable fraction of particulate organic carbon (POMP) than CT-SM; whereas in Chipeni, CA-SM had 0.73 g kg–1 higher POMP compared with CT-SM. CA also improved soil porosity, pore size distribution, and water retention capacity by increasing the proportion of mesopores and micropores compared with CT-SM. Thus, changing management practices from CT-SM to CA has the potential to improve the soil organic matter and soil hydraulic properties across agro-ecological zones in Malawi, which is important for sustainable agriculture. Farmers should be encouraged to minimise tillage, retain residues as mulch on the soil surface, and practice crop rotation.

中文翻译：

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马拉维保护性农业和传统耕作方式下的碳封存和选定的水力特征

保护性农业 (CA) 在撒哈拉以南非洲的小农中得到越来越多的推广，以寻求改善粮食安全，同时维持以农业为基础的农业生态系统的自然资源基础。本研究的目的是调查 CA 和传统耕作对马拉维两个对比鲜明的农业生态区土壤有机碳 (SOC) 和选定水力特性的影响。六名农民在每个地点举办了农场试验，每个农民接受以下处理：CA 与连续单一玉米 (CA-SM)、CA 与玉米-豆科植物间作 (CA-ML) 和连续单一玉米的传统耕作（ CT-SM）。土壤样品于 2015 年 10 月从位于 Chipeni、Chinguluwe、Lemu、和 Zidyana，其中 CA 在六个深度间隔实施了 10 年（2005-2015）：0-10、10-20、20-40、40-60、60-80 和 80-100 厘米。使用未受干扰的岩心样品测定体积密度、土壤水分特征和孔径分布。在所有地点，CA 提高了总 SOC、碳储量和颗粒有机碳的稳定部分。在 Chipeni、Lemu 和 Zidyana 中，CA 下玉米-豆科植物间作的总 SOC 比 CT-SM 高 35%、33% 和 73%。在 Chinguluwe 和 Lemu，CA-ML 的颗粒有机碳 (POMP) 含量分别比 CT-SM 稳定 0.54 和 0.50 g kg-1；而在 Chipeni，CA-SM 的 POMP 比 CT-SM 高 0.73 g kg–1。CA 还改善了土壤孔隙度、孔径分布、与 CT-SM 相比，通过增加介孔和微孔的比例来提高保水能力。因此，将管理实践从 CT-SM 转变为 CA 有可能改善马拉维农业生态区的土壤有机质和土壤水力特性，这对可持续农业很重要。应鼓励农民尽量减少耕作，将残留物保留在土壤表面作为覆盖物，并进行轮作。