Yield of potato ( L.) increased by more than two-folds through nitrogen and phosphorus fertilizers in the highlands of North-Western Ethiopia.

Ethiopia has a huge potential to increase the production and productivity of potato ( L) mainly in north-western regions where current potato yields are less than 10 t ha. Soil fertility and disease are the major yield-limiting factors of potato in this part of the country. Three-year's on-farm research was conducted to get the optimum economic levels of nitrogen (N) and phosphorus (P) nutrients for the major potato-growing areas of north-western Ethiopia. A factorial experiment with four levels of N (46, 92, 138, and 194 kg ha), three levels of PO (46, 69, and 92 kg ha), and one pilot treatment with no NP nutrient inputs was used. A randomised complete block design with three replications was used. The findings of the research showed that more than 40 t haof potato could be attained (about four times the current productivity) in the study areas through NP nutrient management. The yield was increased significantly with an increased rate of N at all sites ( < 0.01). The yield difference was nonsignificant > 0.05) between P levels for most of the sites and years. The financial analysis of the findings for Yilmana Densa district indicated that applying 138 N and 46 PO kg ha, together, gave a marginal return of (Birr/Birr) 70.9, whereas 138 N and 69 PO kg ha resulted in 10.7. For the South Gondar, 138 N and 46 PO kg ha gave a marginal return of 24.3 (Birr/Birr). Therefore, based on the farm gate price of potato and the cost of fertilizer, 138 N, combined with 69 PO kg ha, is recommended for the Yilmana Densa. For the South Gondar, 138 N, combined with 46 PO kg ha, is recommended.