SEQUENTIAL EFFECTS OF MINIMUM TILLAGE, SEED PRIMING, FERTILIZER MICRODOSING AND MULCHING IN MAIZE, SEMIARID CENTRAL RIFT VALLEY OF ETHIOPIA

摘要

Intensification of maize production is imperative to improve food security for the rising population in the central rift valley (CRV) of Ethiopia, whose livelihood is principally based on rainfed maize that operates under shrinking landholding and high seasonal rainfall variability. This study examined different levels of intensification options in maize production by sequentially introducing minimum tillage and seed priming, phosphorus (P) fertilizer microdosing, surface mulching and nitrogen (N) fertilizer microdosing. Field experiments were conducted with five treatments, steps or levels consisting of conventional tillage (farmers practice as a control); minimum tillage + seed priming, unfertilized (step 1); step 1 + microdosing 53 kg ha(-1) P (step 2); step 2 + 4 ton ha(-1) maize stover as surface mulch (step 3) and step 3 + 53 kg ha(-)1 N (step 4). These steps represented increasing levels of intensification. Except at the lowest level (step 1), agronomic and economic responses improved with increasing levels of inputs. Relative to the very high and increasing gross margin, production costs were low but slowly increased with increasing levels of inputs. Except at the lowest level, the value cost ratio was above 4 even at the highest levels of inputs, demonstrating that such kind of intensification can be achieved with low risk. Likewise, the fertilizer use efficiency was quite high even at the highest of levels of inputs signifying the efficiency of the pocket application of fertilizer through the microdosing method. The improvement in maize establishment and yield and the reduction in the days to maturity could contribute to make maize production more adaptive to the existing seasonal rainfall variability. Depending on the affordability to the external inputs and their feasibilities, the different technology packages in the intensification ladder may give different choices for the farmers to improve maize production in the CRV of Ethiopia.