Tied-ridging and fertilizer use for sorghum production in semi-arid Ethiopia

Abstract

Grain sorghum [Sorghum bicolor (L.) Moench] yield is often constrained by low soil water and nutrient availability in Ethiopia. The integration of tied-ridging for water conservation with fertilizer application in semi-arid sorghum production areas of northern and central Ethiopia was evaluated in five trials in 2005–2007. Three tillage practices and four fertilizer application treatments were evaluated in a complete factorial. The tillage practices included tied-ridging before (TR_br) and after (TR_r) the on-set of rains, and shilshalo, a traditional ridging practice for preventing runoff and controlling weeds practiced with the traditional oxen-drawn plow. The fertilizer treatments (N–P) were 0-0, 10-10, 22-0, and 32-10 kg ha⁻¹. Grain yield was increased over shilshalo with tied-ridging by 6–45%. Grain yield was increased by 26% with pre-plant application of N plus P and by 16% with side-dress N application in central Ethiopia, but yield was not increased in the northern Ethiopia trials. Tied-ridging did not increase the yield response to nutrient application. Tied-ridging before or after on-set of rains was found to be equally effective in increasing yields and should be considered for sorghum production in semi-arid areas of northern and central Ethiopia. Response to applied N and P was probably constrained by soil water deficits, even with tied-ridging and especially in the drier environments of northern Ethiopia. Application of N and P should be considered if mean yield levels are above 2.5 Mg ha⁻¹.