2018 Volume 28 Issue 2 Pages 45-58
Soil erosion control initiatives in Mozambique are being conducted by government-related organizations, multiple donor groups, non-governmental organizations, and others, but there are limited quantitative evaluations on the effectiveness of soil erosion control measures at the field level. We evaluated the effectiveness of various soil erosion control measures during the rainy season in Nampula and Lichinga which are located in the Nacala Corridor area of Mozambique. The study was conducted over three years in Nampula using pigeon pea, maize, and cassava, and over two years in Lichinga using pigeon pea and maize. Minimum tillage reduced soil erosion by 57% without a significant decrease in crop yield. Residue mulch from sorghum, maize, pigeon pea, and sunflower reduced soil erosion by 62%, 70%, 90 to 95%, and 51%, respectively. Soy residue mulch did not reduce soil erosion, but roughly doubled crop yield compared with no mulching. Vetiver grass hedgerows reduced soil erosion by 77% and the vetiver grass leaves were impervious to termite damage and limited the spread of termites. Pigeon pea alley cropping provided the same level of soil erosion control as pigeon pea mulch. However, pigeon pea alley cropping did not increase crop yield. From this result, pigeon pea alley cropping is unlikely to be adopted by farmers because this treatment requires more pruning work without a commensurate crop yield increase.
Of the soil erosion control measures we evaluated, minimum tillage combined with crop residue mulch is the simplest to implement, requiring no special materials. We recommend this measure as the best method to reduce both soil erosion and physical labour. In fields with termites, minimum tillage should be combined with vetiver grass hedgerows. Soy residue can increase crop yield but it cannot provide a soil erosion control effect, thus it must be combined with another technique.
