Assessing Soil Degradation with Emphasis on Soil Poductivity to the Ajeni Area
1992
Kefeni Kejela (Ministry of Agriculture, Addis Abeba (Ethiopia))
This paper summarizes the results of soil conservation experiments carried out in West Gojam Administrative Region, Anjeni Station in 1985-1986. Soil conditions with possible influence on productivity, such as effects on texture, nutrient balance, and crop yields, have been described on Luvisols of 28 per cent slope and Nitosols of 12 per cent slope. The sand content of eroded soil samples increased with an increase in slope. The silt plus clay content of eroded soil was generally higher than that of the field surface soil. High N and P concentration were associated with high sediment concentration. The effect of erosion on crop production was high as available nutrients were washed out with sediment. The high soil loss was observed from bare plots where 269-321 t/ha per year were measured. Total enrichment ratios of eroded soil in relation to surface soil were 1:9 N, 1:6 P, 2:1 organic matter, 1:1K, 1:3 Ca, and 1:2 Mg. In extrapolating the findings to the farming systems of Anjeni on a 100 ha plot, it was calculated that on average 31 t of N, 16 t of organic matter, and 68 t of P were lost by erosion.
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