Increased application of nitrogen fertilizer rates and plant densities effect on maize (Zea mays L.) at Nada Sadacha, Southwestern Ethiopia
The field experiments were carried at Nada sadacha waredas, Jimma Zone, for 2017-18 main consecutive cropping seasons. The treatments consisted of factorial combinations of four plant densities (75*20 (66666), 75*25 (53333), 75*30 (44444) and 80*40 (62500 plants h-1) and five Nitrogen and Phosphorous fertilizer rates (69, 92, 115, 138 and 161 N kg ha-1) laid down in an RCBD factorial design with three replications using BH546 variety. All spacings accommodates a single plant per hill except the 80*40 two plants per hill. All grain yield and yield related parameters were significantly affected by N fertilizer rates and plant densities and no interaction. The highest grain (8.66 and 8.73 t/ha) and above ground biomass yield (16.93 and 17.46 t/ha) respectively were obtained from 138 kg ha-1 N fertilizer rate and 75*25 cm (53333 plants h-1). The grain yield was significantly increased by 18.47 and 11.31% over the lowest 69 N kg and 92Nkg ha-1(control) respectively also by 30.88% over lower density 80*40 (62500 plants h-1). In conclusion, a medium maturing variety with the application of 138 N kg ha-1 and 75*25(53333 plants h-1) gave the highest net benefit (29430.30 and 30110.40 EtB ha-1) with acceptable MMR (172.21 and 346.56%) respectively. Therefore, based on input availability and economic feasibility, a medium maturing variety with the application of 138 N kg ha-1 and spacing of 75*25 (53333 plants h-1) taken as optimal and recommended for maize (BH546) variety production under rainfed condition of the study area.