Using Conservation Agriculture to Intensify and Stabilize Agricultural Production in Southern Africa.

Soil erosion and degradation jeopardize food security in many sub-Saharan countries. Many common farming systems employ tillage methods that result in inordinate rates of sheet and gully erosion while achieving maize (Zea mays) yields of less than 1 Mg per hectare in many areas.  Farmers often respond to these low yields by farming more land in an effort to achieve household food sufficiency and security.  The objectives of this research were to use conservation agriculture to intensify production onto more manageable smaller plots of land of less than one hectare.  Results of fertilizer N,P, and K research studies suggest that with adequate fertilizer (100-60-30 kg of N-P-K per hectare), plant population of 45,000 plants per ha, and early planting prior to late December can result in consistent yields in excess of 7 Mg per hectare over the four year study period.  Cover crops that include oat (Avena sativa) and vetch (Vicia villosa) can reduce weed infestations by winter annuals by approximately 90 percent, further reduce soil erosion and have the potential to provide winter forage for livestock.  Monitoring of C sequestration rates of these contrasting tillage systems is ongoing.  This research suggests that conservation agriculture can sustainably intensify subsistence food production in this region and possibly mitigate global production of carbon dioxide, a significant greenhouse gas implicated in climate change.