MwAPATA Institute, Lilongwe, Malawi.
Center for Global Change and Earth Observations, Soils and Cropping Systems Ecology, Department of Plant, Soil and Microbial Sciences, Michigan State University, United States of America.
Sci Total Environ. 2022 Sep 1;837:155758. doi: 10.1016/j.scitotenv.2022.155758. Epub 2022 May 6.
In Africa, achieving sustainable agricultural intensification-increasing agricultural output without deleterious environmental impacts or converting more land for cultivation-will depend greatly on the actions of smallholder farmers and the policies that influence them. Whatever the future holds, the vast majority of farmers right now are small. Using multiple lines of evidence across disciplines, we examine trends in productivity of land and fertilizers in Malawi. Unfortunately, our effort uncovers disturbing trends that indicate intensification and sustainability are at risk. Two time-series datasets of satellite-based vegetative indices show a generally flat but highly variable trend in the productivity of agricultural land with epochs of steep decline. This is notably despite substantial (and successful) government effort to promote fertilizer use. We also compile evidence from several studies over three decades that use field-level data from farmers and suggest substantial declining maize yield response to fertilizer over time. These trends are consistent with soil degradation, the disappearance of fallow land and minimal investment in rehabilitation practices in densely populated areas, putting agricultural productivity in jeopardy. These signs of the harmful impacts that narrow approaches to productivity improvement may be having in Malawi are an early warning sign to policy makers in Malawi and around the continent that a more holistic and nuanced strategy is necessary for sustainable intensification in agriculture.
在非洲,实现可持续的农业集约化(即在不产生有害环境影响或不将更多土地用于耕种的情况下增加农业产量)在很大程度上取决于小农和影响他们的政策。无论未来如何,现在绝大多数农民都是小规模的。我们利用跨学科的多种证据,研究了马拉维土地和肥料生产力的趋势。不幸的是,我们的努力揭示了令人不安的趋势,表明集约化和可持续性正面临风险。两个基于卫星的植被指数时间序列数据集显示,农业土地生产力的总体趋势是平坦的,但高度可变,并有急剧下降的时期。这尤其令人担忧,因为政府一直在大力推广肥料使用。我们还汇集了来自三十年中几个研究的证据,这些研究使用了来自农民的田间数据,并表明随着时间的推移,肥料对玉米产量的反应大幅下降。这些趋势与土壤退化、休耕地的消失以及人口密集地区对恢复实践的投资不足相一致,这使农业生产力处于危险之中。这些迹象表明,狭隘的提高生产力方法可能对马拉维及整个非洲大陆的政策制定者构成了威胁,即需要采取更全面和细致的战略,才能实现农业的可持续集约化。