Nutritional composition of oat (Avena sativa L.) herbage as influenced by variety and NP fertilizer levels in Ethiopia

Abstract

In Ethiopia, limited research has been conducted on optimum fertilizer rates to increase oat yield and nutritional value. Therefore, determining the optimum fertilizer rate for higher fodder yield and nutritional quality is crucial for improving oat. Thus, the study aimed to evaluate the effect of fertilizer rates on fodder yield and nutritive values of oat varieties during 2020/2021 and 2021/2022 cropping seasons at Holetta, in the central highlands of Ethiopia. In a factorial arrangement of randomized complete block design with three replications, the experiment was conducted using three oat cultivars (CI-8251, SRCPX80Ab2291, and Sorataf) in conjunction with eight NP fertilizer levels (0, 25, 50, 75, 100, 125, 150, and 175%). The result showed that variety, fertilizer, and year had significant effects ( P < 0.05) on forage dry matter yield (FDMY), digestible yield (DY), and total digestible nutrient yield (TDNY). Application of 175% fertilizer had advantages of 89.3, 92.5, and 25.3% over unfertilized treatment in FDMY, DY, and TDNY, respectively. Among oat varieties, CI-8251 had advantages of 15.4 and 14.1% over the variety Sorataf in FDMY and TDNY, respectively. Additionally, variety SRCPX80Ab2291 showed a 6.3% DY advantage over variety Sorataf. The second year gave higher FDMY, DY, and TDNY. Crude protein (CP), crude protein yield (CPY), digestible crude protein (DCP), in-vitro dry matter digestibility (IVDMD), total digestible nutrient (TDN), and digestible dry matter (DDM) were all significantly influenced by fertilizer by variety by year interaction effect. Accordingly, the interaction effect of the variety Sorataf cultivated using 175% fertilizer in 2020 gave the highest CP (113.9 g/kg DM), CPY (1.66 t/ha), and DCP (68.2 g/kg DM). Similarly, the variety Sorataf cultivated with 50% fertilizer during the 2021 cropping season had the greatest IVDMD. Moreover, the variety Sorataf cultivated with 100% fertilizer during the 2021 cropping season showed the highest TDN and DDM. Additionally, the Pearson correlation analysis indicated that some of the measured parameters had positive and significant associations. Therefore, the application of 125% (51.3 kg N + 25 kg P/ha) fertilizer could increase the fodder yield and nutritive value in the study area. However, this recommendation should be verified by doing similar research under wider areas of oat-growing environments in Ethiopia.