Impact of conservation agriculture on runoff, soil loss and crop yield on a Vertisol in the northern Ethiopian highlands

摘要

Conservation Agriculture (CA) can be a possible technique to mitigate the reduction in soil quality, to reduce runoff and soil erosion, and can increase in situ moisture conservation, thereby increasing crop yield. This study was carried out on a rainfed field in Tigray, northern Ethiopia. The objective was to evaluate the impacts of CA on runoff and soil loss, and crop yield improvements. The CA practices were introduced on farmers' fields on vertisols since 2005. The experimental layout was arranged according to a randomized complete block design with two replicates. Treatments included conventional tillage (TRAD) which was ploughed 3 times and residue removed, Terwah (TERW) ploughed 3 times, residues removed and furrows made at 1.5 m distance, and permanent beds (PB) with 30% residue retention, zero tilled and 60 cm wide bed size. All the ploughing and reshaping of the furrows was done using the local ard plough maresha. Data on soil loss, runoff and grain yield were collected. The crops in rotation were wheat and teff. There was significant reduction (p<0.05) in runoff in PB under wheat in 2005, whereas the reduction was nonsignificant in 2006 and 2007. The soil loss was significantly lower in PB in 2005 and 2006. Soil loss in 2005 under wheatwas reduced by 76% in PB and 61% in TERW as compared to TRAD. Similarly, the reduction in soil loss in 2006 under teff was 86% in PB and 53% in TERW. There was no significant difference (p<0.05) for wheat yield in 2005 and 2007. However, there was a significant difference among treatments in 2006 with higher teff yield in TRAD followed by TERW. In summary, permanent bed reduced soil loss and runoff and hence increased yield of wheat. Yield of teff was, however, reduced with permanent beds.