Effect of rainfall variability on crop yield under semi-arid conditions at sub-catchment level

Abstract

Poverty, hunger and malnutrition amongst rural people in semi-arid areas where small scale farming is dominant are widely recognized as major problems. The fact that rural communities of southern Africa reside in marginalized areas which are characterized by low and highly variable rainfall that is poorly distributed exacerbates these problems. Most of their attempts at farming activities result in yields that are way below the expectation of farmers. Sometimes these dryland farmers experience complete crop failure leaving them with nothing to live on, or let alone sell and earn the much needed income. So how then, can a growing community whose main means of survival is at the mercy of nature feed itself? The challenge at hand is to determine how crop productivity can be improved in semi arid areas in the wake of erratic and low rainfall. This research is in line with both the Millennium Development Goal (MDG) number 1, which is to eradicate extreme poverty and hunger and the Poverty Reduction Strategy (PRS) which aim to increase national food security. Also the fight against the negative impacts of HIV/Aids cannot be won without the necessary basic nutrition. This investigation tried to investigate the effect of rainfall variability on crop yield under semi-arid conditions at meso-catchment level. Ten portable raingauges were installed at ten locations within Zhulube meso-catchment based on direction of prevailing wind and soil type. In addition to this, seven 10m*10m experimental maize plots were cultivated and a household survey was carried out to assess the farming practices that prevail in the area in order to understand their possible impacts on crop yield. Results have revealed that while there was temporal variability of rainfall in the study area, it was significant in the long-term and insignificant in the short-term. Spatial variation of rainfall was significant in Zhulube meso-catchment in the short-term. It was however not significant enough to cause significant differences in yield. Results from the household survey indicated that despite the villages cultivating common crops with maize being the most common, they exhibited variation in most of the critical farming practices.