Biomass production and nutritional quality of potato tuber as affected by blended fertilizer (NPSB), cattle manure, vermicompost and mineral NP in southwestern Ethiopia

Keeping in view the declining soil fertility and people's nutritional issues, a research experiment on potato (Solanum tuberosum L.) was carried out in Belg (February to May) and Meher (June to October) seasons of 2020 at Abelo in Masha district, southwestern Ethiopia, to gauge the effects of blended mineral NPSB fertilizer, cattle manure (CM), vermicompost (VC) and mineral NP on growth, biomass and tuber nutritional quality. The fertilizer treatments consisted of 7.5 t CM h(-1) + 75 and 50% of recommended dose of NP fertilizers (RDF), 7.5 t VC h(-1) + 75, 50 and 25% of NP, 5 t VC h(-1) + 75% NP, 100 kg NPSB h(-1) + 61.5 kg P h(-1) + 146 kg N h(-1), 150 kg NPSB h(-1) + 53.7 kg P h(-1) + 138 kg N h(-1), 200 kg NPSB h(-1) + 46 kg P h(-1) + 128 kg N h(-1), 100% of NP (165 kg N h(-1) + 60 kg P h(-1)) and one nofertilizer treatment (control) making a total of 11 treatments. The effects of the treatments indicated that the application of 75% of NP and 7.5 t h(-1) vermicompost significantly increased the plant height, dry shoot and root yields, specific gravity, total soluble solids and starch. On the other hand, the highest crude protein content was recorded at the application of 200 kg NPSB h(-1) + 46 kg P h(-1) + 128 kg N h(-1). It was summarized that the use of 7.5 t VC h(-1) + 75% of NP (124 kg N h(-1), and 45 kg P h(-1)) increased the biomass and improved the quality of potato fetching high economic return over the sole application of either 200% mineral NPSB h(-1) or 150% mineral NPSB ha or 100% NP or no-application of fertilizer in the study area. In the light of present findings, there is a need to extend these studies using multiple combination ratios of NPSB fertilizer with vermicompost and cattle manure on different soils of varied agro-climatic zones to come up with conclusive recommendations.