Effects of fertilizer levels and varieties on fodder yield productivity, nutrient use efficiency, and profitability of oat (Avena sativa L.) in the central highlands of Ethiopia

This study aimed to assess the effect of fertilizer rates on agro-morphological traits, nutrient uptake and use efficiency, and economic feasibility of fodder yield in oat. The study was carried out using a factorial arrangement of eight fertilizer rates (0, 25, 50, 75, 100, 125, 150, and 175 %) and three oat varieties (CI -8251, SRCPX80Ab2291, and Sorataf) in a randomized complete block design with three replications. The results revealed that variety, fertilizer, and year had a significant effect on fodder yield. The fodder yield increased up to 175 % of the blanket recommended fertilizer and application of 100, 125, 150, and 175 % produced fodder yield of 14.0, 15.6, 15.8, and 15.9 t/ha, respectively. The fodder type oat (CI -8251) and dual type oat (SRCPX80Ab2291) variety had 15.4 and 10.6 % fodder yield advantages over grain type oat (Sorataf), respectively. Significantly higher fodder yield was obtained in 2021 than 2020 cropping season. Moreover, the interaction effect of variety by fertilizer by year was significant for nitrogen and phosphorus concentrations, nitrogen and total nutrient uptake, partial factor productivity, internal utilization efficiency, agronomic efficiency, and agro-physiological efficiency. The Pearson correlation analysis indicated that the number of tillers per plant, yields of morphological fractions (leaf, stem, and panicle), forage yield production rate, nutrient concentration, and uptake had significant positive associations with fertilizer levels and fodder yield. In contrast, all nutrient use efficiency except agro-physiological efficiency had inverse associations with fertilizer levels and fodder yield. The combined partial budget analysis for the three oat varieties showed that the application of 125 % fertilizer produced a higher net benefit (83,440 ETB) and marginal rate of return (12,635.6 %). Therefore, the blanket recommended fertilizer rate of 125 % (51.3 kg N + 25 kg P/ha) could increase fodder yield and farm profitability in the study area.