Maize-based conservation agriculture systems in Malawi: Long-term trends in productivity

Continuous maize cultivation in Malawi has degraded the soils, but conservation agriculture (CA) offers an option for improving soil quality while increasing yields. However, the effect of CA can vary widely by agro-ecological context. This study evaluates this effect by comparing CA productivity trends in nine communities in the southern and central regions of Malawi. In each target community six experiments were established which applied three treatments: conventional ridge and furrow system with maize; CA with maize and CA with maize and a legume intercrop. Variability among communities was explored using principal component analysis. Site characteristics, seasonal effects, and cropping system (CA or conventional) were found to significantly impact maize grain yield. CA cropping systems had higher time-to-pond than conventional, suggesting improved water infiltration. Improvements in yield as a result of CA production systems were universal across all communities, despite vast differences in biophysical characteristics. However, these yield improvements were not immediately significant, becoming evident after three to five seasons.