Research on conservation agriculture and associated practices in eastern Zambia
Declining soil fertility and a changing climate requires sustainable cropping systems that improve productivity and profitability while adapting to climate variability without negative environmental side effects. Since 2011, agricultural researchers in eastern Zambia have focused on the use of conservation agriculture (CA) systems and associated practices that improve soil fertility and strengthen farmers’ adaptive capacity against drought and heat stress.
CA is a cropping system based on the principles of a) minimum soil disturbance; b) crop residue retention and c) crop diversification. The combined use of these three principles distinguish it from other crop management systems such as Integrated Soil Fertility Management (ISFM), soil and water conservation or agroforestry. However, in mixed crop-livestock systems the three CA principles are not enough. Complimentary practices such as appropriate fertilization, weed control, integration of green manures and agroforestry species among other measures are required to make CA functional in this context.
In eastern Zambia both manual and animal traction CA systems were tried in combination with rotation and intercropping of maize with soybeans and cowpea. Increasingly, CA research focused on associated practices such as (a) doubled-up legume systems; (b) the use of Gliricidia leaves in intercropping systems; (c) maize/pigeon pea intercropping; (d) maize/lablab intercropping; and (e) pigeon pea ratooning to improve its functionality.
This poster presents research evidence from eastern Zambia that shows that CA systems may lead to maize yield benefits of up to 81% (1,788 kg ha-1) and 66% (1,380 kg ha-1) if farmers rotate with cowpea or soybean, respectively. Increased net benefits (5-150%) have been recorded over time due to increased returns on investment (USD 1.3 more per USD invested) and returns on labour (USD 13.3 more per labour day invested) than conventional practices. Other regional research results published in numerous papers show that environmental benefits of CA are increased water infiltration, greater soil moisture content, reduced erosion and water run-off, increase in soil carbon and climate resilience over time. Other more social benefits are reduced labour for seeding and weeding (25-35 labour days ha-1) which preferentially benefits women and children.
CA systems have been scaled by numerous players in eastern Zambia and approximately 50,000 farmers have been reached with the help of Total LandCare, Catholic Relief Services (CRS), the Conservation Farming Unit and governmental research and extension services during the different phases of Africa RISING. Since 2015, the International Maize and Wheat Improvement Center (CIMMYT) is working closely with CRS and Grassroots Trust to scale up maize/pigeon pea systems to 5,000 farmers. So far 1,350 registered growers are planting the crop and more than 300 have already marketed it.
However, future research is still required to better quantify the human and social benefits of CA systems in the region, besides the biophysical benefits that have already been documented, in the short- and long-term.
The combined use of CA principles is a pathway to more resilient farming systems that can increase the food and nutrition security and dietary diversity of smallholder farmers in eastern Zambia.
The poster was presented at the Africa RISING ESA Project review and planning meeting in Lilongwe, Malawi on 3–5 October 2018.