Impact of tillage and soil amendments on cereal production in the Sahelian Zone of Mali

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A field study was carried out at Sikidolo in the Sahelian zone of Mali to assess the impact of tillage and soil amendments on the growth and yield of millet and sorghum. Two experiments were conducted for millet and for sorghum. The treatments consisted of two tillage practices (contour ridge and hoe tillage) and five soil amendments (organic manure, urea, rock phosphate and lime). The experiment was factorial in RCBD with 3 replications. The contour ridge outyielded the hoe tillage in most of the measured parameters. The respective percentage increment under millet and sorghum were 12.5 and 9 % for plant height, and 12 and 61 % for grain yield. Millet biomass yield and nitrogen use efficiency (NUE) were increased by 65 % and 316 % respectively by contour ridge. Contour ridge did not significantly (p<0.05) influence soil pH, exchangeable K, and available phosphorus, although it had higher values than the hoe tillage and significantly increased soil organic carbon under millet (48 %) and sorghum (15 %). The application of manure increased sorghum height by 94 %, grain yield by 576 % and biomass yield by 162 % while it increased millet height by 61 %, grain yield by 112 % and biomass yield by 198 % relative to the no amendment. The application of manure for both millet and sorghum did not significantly (p < 0.05) affect soil chemical properties, although soil organic carbon value was highest with the application of manure. The integrated use of manure and inorganic fertilizers increased sorghum and millet growth, yield and NUE relative to the application of the manure but did not significantly increase soil chemical properties relative to the application of manure alone. With a value cost ratio (VCR) less than 2.0, all the treatments were not economically profitable. However, on a relative basis, the application of manure was promising with a VCR of 1.8 and 1.0 under millet and sorghum respectively. Based on grain yield and iv corresponding absolute monetary value, the contour ridge was more profitable than the hoe tillage.
A thesis submitted to the Department of Crop and Soil Sciences, Faculty of Agriculture, College of Agriculture and Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirement for the award of the Degree of Master Of Science in Soil Science