Climate-smart Soil Fertility Improvement Techniques Increase Grain Yield in the Ethiopian Highlands

摘要

Subsistence agriculture, the mainstay of the Ethiopian economy, is challenged by declining soil fertility. Smallholder farmers recognize the spatial variability of soils within farms and often apply recommended rates of fertilizer. Taking the responseof wheat (Triticum aestivum L.) to N and P fertilizers (rates increased from 0-0 to 69-69 kg N-P ha"1), grain yield significantly increased. However, the critical nutrient levels of various soils are less known. Setting maximum yield that received 69 kgN ha"1, the critical soil phosphorus concentration was found to be about 6 mg kg"1 for the Vertic Cambisol (Table 1), 4.32 mg kg"1 for the Arenic Cambisol, 5.89 mg kg'1 for the Pellic Vertisol, and 6.62 mg kg"1 for the Calcaric Regosol. Thus, for some soil types in northern Ethiopia, it was actually found that P rates, in terms of DAP equivalent, would have been 124 kg DAP ha"1 for the Vertic Cambisols, 80 kg DAP ha"1 for the Arenic Cambisols, 129 kg DAP ha"1 for the Pellic Vertisols, and 134 kg DAP ha"1 for the Calcaric Regosols. These results suggest that the blanket fertilizer recommendations that the agricultural extension service set at 50 kg DAP ha"1 for dry areas or 100 kg DAP ha"1 for wet areas need to be revised.