Effect of dry wheat straw mulching and cowpea-maize intercropping on soil erosion and maize yield in Zambia

Past and present-day erosion is a significant form of land degradation that has rendered vast areas of sloping land unproductive with respect to crop production. Thus, conservation tillage, along with complementary practices such as soil cover and crop diversity has become a better option to ensure sustainable food production and maintenance of environmental sustainability. A field study was conducted to evaluate the effect of dry wheat straw mulching and cowpea-maize intercropping practices on soil erosion and maize yield. The field experiment was conducted at the University of Zambia, Great East Road Campus Field Station, in Lusaka, which is managed by the School of Agricultural Sciences. The study aimed at assessing the effect of mulching and intercropping practices on soil erosion and runoff, water balance and components of the Universal Soil Loss Equation. The study was carried out in the 2016/2017 rainy season with maize as a test crop. A randomized complete block design was adopted with three replicates. Treatments were (i) dry wheat mulching, (ii) cowpea-maize intercropping and (iii) conventional practices. The results showed that the use of dry wheat straw mulch at the rate of 12 ton/ ha could reduce the amount of soil lost by 14 % as compared to the intercropping practice. The runoff was not significantly affected by the dry wheat mulch and cowpea-maize intercrop. The annual soil loss predicted from the Universal soil loss equation was significantly reduced by 58 % in the dry wheat mulch and 29 % in the cowpea-maize intercrop as compared to the conventional practice. The non-significance of the maize yield obtained would have been due to the infestation of Army worms during the maize tasselling stage.
Key words: soil loss, runoff, conservation tillage, crop diversity