Effects Of Soil And Water Conservation Technologies On Sediment And Maize Yield In Tharaka-Nithi And Embu Counties Of Kenya

ABSTRACT

Decline in crop yields in Tharaka-Nithi and Embu counties is linked to poor agricultural practices and climate variability. Research has reported positive results from implementation of mulching, tied ridging, minimum tillage and intercropping. This study was set up to: i) determine effect of soil and water conservation technologies on runoff ii) evaluate effect of the technologies on sediment and nutrient loss iii) investigate effect of the technologies on maize yield, and iv) analyze economic implications of the technologies. The study was conducted in Meru South and Mbeere South sub-counties for two consecutive cropping seasons; Long rains 2011 and short rains 2011. A randomized complete block design was adopted with 3 replicates. Treatments were Mulching, MBILI intercrop and conventional in both sites, minimum tillage in Meru south and tied ridges in Mbeere south. Conventional tillage was the control treatment. Key variables measured were runoff, sediment yield, nutrient concentration in sediment, grain yields, economic and weather data. Data was subjected to Analysis of Variance using SAS 9.1.3. Mean separation was done using Fisher‟s LSD at 5% level of significance. Compared with control results showed that in Meru South, mulching and MBILI intercrop reduced runoff by 26% (p=0.04) during short rains 2011; sediment yield was reduced by 41 and 12% under mulching and MBILI intercrop respectively, during long rains 2011 (p=0.03) and by 71, 61 and 68% (p=0.01) under mulching, MBILI intercrop and minimum tillage respectively, during short rains 2011; Mulching and MBILI intercrop reduced N concentration by 29 and 35% respectively, during long rains 2011 (p=0.02). During short rains 2011, mulching, MBILI intercrop and minimum tillage reduced N concentration by 61, 33 and 46% respectively (p=0.01). Potassium concentration was reduced by 55, 40 and 44% under mulching, MBILI intercrop and minimum tillage respectively, during short rains 2011 (p=0.02). Organic carbon concentration was reduced by 54, 30 and 46% during long rains 2011 (p=0.01) and by 54, 33 and 39% during the short rains 2011 (p=0.01) under mulching, MBILI intercrop and minimum tillage respectively. Maize yield was increased by 5, 40 and 7% under mulching, MBILI intercrop and minimum tillage respectively (p=0.001) during long rains 2011. Net benefits under mulching, MBILI intercrop and minimum tillage were increased by 11, 75 and 16% respectively, during long rain 2011 (p=0.001). Benefit cost ratio increased by 27, 77 and 54% during long rains 2011 (p=0.004) and by 33, 44 and 89% during short rains 2011 (p=0.02) under mulching, MBILI intercrop and minimum respectively. In mbeere south, runoff was reduced by 52% and 49% during long rains 2011 and by 51% and 30% during short rains 2011under tied ridging and mulching, respectively. Mulching, MBILI intercrop and tied ridging reduced sediment yield by 78, 50 and 71% during long rains 2011 (p=0.01) and by 53, 29 and 64% during short rains 2011. Potassium concentration was reduced by 53, 19 and 47% during long rains 2011 and by 33, 13 and 54% during short rains 2011 under mulching, MBILI intercrop and tied ridging respectively. Organic carbon concentration was reduced by 54, 22 and 50% under mulching, MBILI intercrop and tied ridging respectively, during long rains 2011. Mulching reduced organic carbon concentration by 58% during short rains 2011. Total crop failure occurred during long rains 2011 due to erratic rainfall. During short rains 2011 tied ridging and mulching increased maize yield by 94 and 75% respectively. Tied ridging, mulching and MBILI intercrop increased net benefits by 228, 205 and 127% (p=0.01) and BCR by 280, 260 and 120% (p=0.004) respectively. The soil and water conservation technologies performed better than the control in all parameters evaluated.