Integrated Use of Cattle Manure and NPS Fertilizer to Improve the Yield of Grain Amaranth (Amaranthus caudatus L.) in Southwest Ethiopia

There is a need to optimize the modus operandi of fertilizer beneath farmers’ situations, mainly its application alongside organic resources. The study is aimed at investigating the effect of combined application of NPS blended fertilizer and cattle manure on growth, yield attributes, and yield of grain amaranth. The experiments were conducted in 2020 main cropping season in 3 localities, i.e., Guraferda, Menitgoldiya, and Menitshasha woredas in Southwest Ethiopia. The treatments were consisted of four NPS blended fertilizer levels (0, 20, 40, and 60 kg·ha−1) and four cattle manure series (0, 4, 8, and 12 t·ha−1). The experiment was laid out as a randomized complete block design (RCBD) in a factorial arrangement and was replicated 3 times. The effects revealed that the combined efficacy of NPS blended fertilizer and cattle manure significantly affected the days to flowering, days to physiological maturity, plant height, panicle length, number of panicles per plant, weight of thousand-grain, above-ground biomass yield, and grain yield. The highest amaranth grain yield of 1264.4 kg·ha−1 was recorded with 60 kg NPS fertilizer ha−1 and 12 t cattle manure ha−1 in combination followed by 60 kg NPS fertilizer ha−1 + 8 t cattle manure ha−1. The partial budget analysis indicated that the highest price 22759 ETB ha−1 was received from 60 kg·ha−1 NPS fertilizer and 12 t·ha−1 cattle manure. The results of this study indicated that application of 60 kg·NPS ha−1 in mixture with 12 t·ha−1 cattle manure is the best combination to achieve the maximum yield in the study areas. Therefore, in light of the significant response of amaranth to organic and inorganic fertilizer, further studies aimed at promoting integrated soil fertility management and formulation of fertilizer recommendation on yearly soil and plant test bases over locations will be useful.