Influence of Mineral Nitrogen and Potassium Fertilizers on Ware and Seed Potato Production on Alluvial Soil in Eastern Ethiopia

Abstract: Potato (Solanum tuberosum L.) is an important food security and cash crop in Ethiopia. However, the yield of the crop is low in the country due to a number of factors among which poor soil fertility management is a major one. Therefore, a field experiment was conducted on the main campus of Haramaya University in the 2009/10 cropping season to elucidate the effect of mineral nitrogen and potassium fertilizers on growth and tuber production of the crop. The treatments consisted of five rates of nitrogen (0, 50,100,150, and 200 kg N ha-1) and three rates of potassium (0, 100, and 200 kg K2O ha-1). The experiment was laid out as a randomized complete block design in a factorial arrangement and replicated three times per treatment. The results of the experiment revealed that nitrogen had significant main effects on all parameters except tuber specific gravity whilst potassium did not influence any of the parameters studied. The maximum marketable ware potato tuber yield (21.4 t ha-1) was obtained in response to the application of 100 kg N ha-1. However, the highest yield (12.7 t ha-1) and number (5.2 tubers hill-1) of medium-sized tubers, which are appropriate for planting as seed, were attained at the rate of 200 kg N ha-1. Thus, it could be concluded that the rate of nitrogen fertilizer required to enhance seed tuber production was found to be higher than that required to optimize ware potato production, and potassium application was not necessary to produce the crop. Keywords: Soil properties; Solanum Tuberosum L.; Tuber number; Tuber Size Distribution; Tuber Yield