Grain yield response of sorghum (sorghum bicolor) to tied ridges and planting methods on Entisols and Vertisols of Alemaya area, eastern Ethiopian highlands

摘要

Field experiments were conducted under rain-fed conditions between 1986 and 1995 to investigate the effects of soil and water conservation treatments (tied ridges and planting methods) on the yield of an improved sorghum variety (ETS-2752) grown with and without N and P fertilizers on two major soils of Alemaya area, eastern Ethiopian highlands. The yield responded significantly (P less than or equal to 0.01) to the treatments both under fertilized and unfertilized conditions of the soils studied. However, the magnitude of the yield response and the relative efficiency of the tied ridges and planting methods varied with soil type, fertilization, and total rainfall and its distribution during the cropping season. Regardless of the type of tied ridge used, furrow planting, specifically, closed end tied ridge planting in furrows gave the highest yield in three of the four sets of experiments. Flat bed planting produced the lowest grain yields on all sets of experiments except under the unfertilized condition of Entisols in which open end planting on ridges produced the lowest sorghum yield. Within the tied ridges, closed end performed better than open end in all except the Vertisols without N and P fertilizers. Compared with the traditional. (flat bed) planting method, the highest yield increment of 1361 kg/ha (34.5%) due to tied ridges was obtained on the Entisols with NP followed by 1255 kg/ha (48.5%) on the Alemaya black clay soils (Vertisols) under fertilized condition, indicating that the yield response to water conservation treatments was higher under fertilized than under unfertilized conditions on the two soils. Fertilization increased the yield of sorghum by as high as 1576 kg/ha (69.5%) on Vertisols and by 1468 kg/ha (38.3%) on Entisols both from planting in the furrows of closed end tied ridges. The study also revealed that the yield response was higher in seasons with low or poorly distributed rains and on shallow and coarse textured soils. The results indicate that in areas with low and erratic rainfall such as the Alemaya area, soil and water conservation is indispensable for increasing crop yield.