Conservation agriculture, which involves minimum tillage of the land and retaining crop residues on the land, has proven useful for increasing yield and at the same time managing soil fertility and increasing farmers resilience to drought and climate variability in Malawi. However, so far the technology has mainly focused on maize. Can the technology be expanded to other crops?
The early win project Sustainable Intensification and Diversification of Maize-based Farming Systems in Malawi led by Washington State University (WSU), evaluated three farming systems – continuous no-till maize, conservation agriculture for sweet potato and cassava, and conventional farming for sweet potato and cassava – to explore if other crops can grow well under conservation agriculture.
The project also introduced intercropping of pigeon pea with the cassava and sweet potato to intensify production to not only increase food production but also improve household nutrition and reduce protein and micro-nutrient deficiencies, and enhance soil fertility and quality.
The study was carried out in 2 districts in Malawi, Dowa and Nkhotakota, and on four farms in each district. On each farm the three farming systems were analyzed for their impact on food production, human nutritional outputs, soil fertility, soil moisture, and household income.
Sweet potato yields were poor under conservation agriculture relative to conventionally farmed sweet potatoes. This, says Dan TerAvest of Washington State University and one of the researchers, shows that further research is needed before some crops can be promoted in conservation agriculture systems.
“In conservation agriculture, the land is not tilled and herbicides are used to control weeds. The residue from the harvested crops is left on the land as mulch. In central Malawi, most residues are taken off the land as mulch for tobacco seedlings, used for household cooking, or burned off the field to ease tilling of the land. This leads to the soils having less moisture and organic carbon, reduces yield,’ TerAvest said.
“Residue on the land also helps buffer soil temperature. We looked at soil temperature at 20 cm depth on land under conservation agriculture (with residue) and under conventional (without residue) and found less temperature variation and lower temperatures where residues were present,’ he said. Leaving residues on the land lead to increased rain water use efficiency, which can be crucial for food security, especially in low rainfall areas.”
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(Article by Catherine Njuguna)
The Africa RISING program comprises three linked research-for-development projects, funded by the USAID Feed the Future Initiative, and aiming to sustainably intensify mixed farming systems in West Africa (Southern Mali and Northern Ghana), the Ethiopian Highlands and East and Southern Africa (Tanzania, Zambia and Malawi).
To produce some short-term outputs and to support the longer term objectives of the projects, in 2012 Africa RISING funded several small, short-term projects in each of the regions. More information.