On-farm Quantification and Demonstration of the Extent of Soil Erosion and Nutrient Loss from Slope Farmland Under Millet Production in Kafa Zone, Ethiopia

Abstract

The study was conducted in Gimbo woreda, kafa zone on soil erosion extent and its risk. The survey result on soil loss in area showed that more than 70% soil erosion occurs on the first month after finger millet sowing. 22x2m runoff plots were laid on six farmers field on which finger millet was sown. The trial farmers were selected based on slope category of farmlands (three farmers with above 10-15% and other three farmers above 16-20%) using FRG (Farmers Research Group) approach with the support of JICA FRG project in 2013. After conducting the erosion measurement during millet production, soil loss was observed to be 61ton/ ha/yr under untreated plot (free plot), 53t/ha under farmer practice and 21t/ha under introduced erosion control. The mean of soil loss under three different treatments over three farmers in slope above 10-15% was 21t/ha. Similarly, the mean of soil loss under three different treatments over three farmers in slope range above 16-20% was 45t/ha resulting to 2.2mm soil layer lost per year under millet production. The soil loss from any land under millet production varied from that of introduced type of soil conservation and farmer practice of soil conservation methods by 40 and 32t/ha respectively. This shows that during millet production on slope land above 16-20%, areas treated by farmer practice and those untreated by any conservation practice exceeded that of introduced soil conservation practice by 150% and 190% respectively indicating that, applying their practice of soil erosion control, farmers could save at least 8t/ha soil from slope land and 4t/ha soil from less slope land during millet production. According to LSD at p=0.05 the soil loss from any land under millet production will vary from that of land with erosion control and farmer practice method of control by 15 and 4t/ha respectively. Areas treated by farmer practice and those untreated will exceed that of introduced soil conservation area by 40% and 60% respectively. The result of study on economic analysis showed that a farmer with such soil erosion in the area will invest 30kg N (65kg Urea) more than blanket recommendation on his land to maintain fertility of his land. It will be 142% cost of fertilizer relative to normal application rate.  Farmers during discussion rose possible causes of soil loss in the area were, frequency of tillage during millet production (4-5tmes); Millet is sparsely planted and open throughout the production times and this situation aggravates erosion; Compaction of soil (trampling by animals) during planting; Cultivation of high slope (>15%) farm land for millet and the high and erosive rainfall during the planting season (Jun/July).  To solve the problems, millet production should be done with proper SWC works; Slopes above 15% should be treated with 5-6m Contour interval for SWC activity; During watershed development planning, special attention should be given for millet producers in order to reduce soil erosion; Use of strip cropping with width of the strip for a crop (millet or other) not more than 10m and farmers need to be organized for further agricultural experiment through FRG principle as it empowers them to solve their own agricultural productivity problem.

Keywords: Soil loss, Soil erosion, FRG, runoff plots, slope range, millet production