The Influence of Rainfall Season Quality on Maize Yield under Conservation Agriculture on Some Selected Locations in Malawi

Abstract

Conservation agriculture (CA) is becoming an important option for integrated land and water resources management in most parts of the Sub-Saharan Africa region. Minimum soil disturbance, maximum soil cover, and crop rotations are the cornerstones of CA. The popularity of conservation agriculture is growing because, not only does it promise to improve yields, it simultaneously improves the environment from which the food crops are being produced. The former being important for Millennium Development Goal number one and the latter for goal number seven. An attempt was made to contribute towards the advancement of the CA technology, by defining the rainfall season quality in which CA would produce optimum yields for maize. Implementing CA within this rainfall season quality would enhance efficient utilization of rain water. Efficiency is one of the cornerstones for attaining integrated water resources management, both at the catchment and basin level. The Water Requirement Satisfaction Index, computed using the AgroMetShell, was used to characterize rainfall seasonal quality. The characterization was in such a way that as the index approaches 100, the quality of that season is considered very good and crop performance is expected to be approaching its potential. The average grain yield for maize and rainfall records for 34 farmers from 6 districts in Malawi, namely, Balaka, Dowa, Machinga, Nkhotakota, Salima and Zomba were used. The rainfall season quality at Extension Planning Area (EPA) and at farmer level was established for these 34 farmers. The interpretation that yield increases with an increase in the WRSI was tested both at EPA and farmer level. The average grain yield from conservation agriculture was compared with that from a conventional farmer’s practice at a given rainfall seasonal quality. At EPA level, it was found that only in 1 district, Salima, did crop performance increase with an increase in the WRSI. This increase however was not statistically significant. At farmer level, 10 out 26 crop performances followed the interpretation of the index. Out of the 10, only 1 crop performance, for Dowa in 2009 was statistically significant at p=0.05. There was no significant difference between the average grain yield obtained from conservation agriculture and the average grain yield obtained from conventional farmers practice, at a given rainfall season quality. However the yield gains from CA in relation to farmers’ conventional practice increased with time. The Water Requirement Satisfaction Index was thus found not to be the most suitable tool for advising whether CA can be implemented in an area or not in Malawi.