Response of Potato (Solanum tuberosum L.) to Nitrogen and Phosphorus Fertilizers in Asagirt District of North Shewa, Ethiopia

Abstract

Potato is a vital crop in Ethiopia’s middle- and high-altitude regions, particularly in the North Shewa highlands, where it is the primary Belg (short rainy season) crop after barley. However, production is hindered by low soil fertility, erosion, nutrient depletion, poor crop management, and suboptimal fertilizer application. An on-farm experiment was carried out to evaluate potato performance under various levels of nitrogen and phosphorus fertilizer in the 2020 and 2021 Belg planting seasons on four farm fields in Asagirt District, North Shewa Zone, Ethiopia. A factorial experiment comprising four amounts of N (23, 46, 69, and 92 kg N ha -1) and three amounts of P (23, 46, and 69 kg P2O5 ha -1), along with a control treatment (0, 0) N and P2O5, was carried out via a randomized complete block design (RCBD) involving three replicates. Tuber yield, growth, and soil data were measured and subsequently analyzed using Statistical Analysis System software. The results revealed a substantial (p<0.001) effect of N fertilizer on key tuber yield and growth parameters. In contrast, P rates and their interaction with N did not affect most parameters. The highest marketable tuber production of 25.50 tons ha-1 was attained from a nitrogen rate of 92 kg N ha-1. For phosphorus, the highest yield (22.71 tons ha-1) was achieved with 69 kg P2O5 ha-1, whereas the no input treatment yielded the lowest (18.68 tons ha-1). According to the economic analysis, the greatest marketable yield (26.52 t ha-1) and the highest benefit-cost ratio (2.67) were achieved with an application of 92 kg N ha-1 and 46 kg P2O5 ha-1. Therefore, this fertilizer combination is recommended as the optimal rate for potato production in Asagirt and similar agroecology during the Belg season until further N and P rates are determined through multilocation studies.