Validation of Recommended NP Fertilizer Rates along with Potassium Application for Wheat Production in Omo Nada District, Southwest Ethiopia

Abstract

Inorganic fertilizer application is among the major factors help to improve crop productivity. Use of fertilizersfor major cereal crops, including wheat, was started in Ethiopia before forty years; even though the recommendation still remained more general. The current scenario of fertilizer requirement is moving towards soil and crop specific recommendations. This study was conducted to evaluate the feasibility of previous and current NP blanket recommendations for wheat production on Andosol. It was carried out in Cheleleka Donga kebele ofOmo Nada district in Jimma zone, Oromia Regional State, south western Ethiopia during the crop season of 2019 on farmers’ field. N and P rates recommended at various times were used as a base for treatment setting. Accordingly, two rate of N (64 and 73 kgN/ha), three rates of P2O5 (37.7, and 69 kg /ha) and three rates of K2O (0, 18 and 36kg/ha)were used.The experiment was laid downin a randomized complete block (RCB) design with a 2*3*3 factorial treatment arrangement in four replications.The soil analysis result showed that it is strongly acidic, deficient in available phosphorus, optimum in total nitrogen and organic carbon and high in available potassium. The differences among fertilizer treatments were not significant for plant height(PH), leaf area index(LAI) and biomass yield (BMY). Spike length was significantly influenced (P < 0.05) by nitrogen rate. Spikelet per spike was significantly affected by the interaction of Pand K. Number of seeds per spike was significantly influenced (P < 0.05) by the interaction of N and K. Thousand seed (kernel) weight was significantly affected (P < 0.05) by K rate. Grain yield was only significantly affected(P < 0.05) by P rate and the maximum value (4574 kg/ha)was obtained when 69kg/ha P2O5 was applied, followed by 46 kg/ha P2O5 with grain yield of 4323kg/ha , with the respective yield advantage of 12.74% and 6.56% over the minimum rate (37.7 kg P2O5/ha). The maximum net benefit was recorded for plots which received 69kg/ha P2O5 with MRR of 258%. In general, Phosphorus was found to be the major limiting nutrient and, hence, improving its availability through improving soil pH and applying enough amount of fertilizer would enhance wheat production in the area.