Abstract:
Potato is an important food security and cash crop in eastern Hararghe Zone. However, the productivity of the crop is constrained by low soil fertility and poor fertilizer management practices. Therefore, a field experiment was conducted at Haramaya watershed in Haramaya District, Eastern Ethiopia; during the 2014 using irrigation. The main objective of the study was to assess the effects of integrated nutrient management on potato growth, yield and yield components and selected physico-chemical properties of soils. The treatments were three rates of farmyard manure (0, 5, 10, t ha-1), three rates of N (0, 55.5, 111 kg N ha-1), and three rates of phosphorus (0, 46, 92 kg P2O5 ha-1). The experiment was laid out as a randomized complete block design in (RCBD) in a factorial arrangement with three replications. The results showed that the effect of integrated use of organic and inorganic fertilizer had significant influence on plant height, above ground biomass, day to maturity, total tuber yield, average tuber number/hill, average tuber mass/hill, marketable tuber number and tuber dry matter yield. The highest marketable tuber yields of 38.65 t ha-1 followed by 36.24 t ha-1 were obtained in response to a combined application of farm yard manure, N and P at the rates of 10t FYM ha-1+111 kg N ha-1+92 kg P2O5 ha-1and 10 ton FYM ha-1+ 111 kg N ha-1+46 kg P2O5 ha-1, respectively. The marketable and total tuber yields were positively and significantly correlated with all growth and yield components studied but negatively and significantly correlated with the number of main stem/hill, unmarketable tuber yield. Application of farm yard manure with N and P increased soil organic matter, available P and total N contents of the soil by 5.31%, 30.1%, and 2.5%, respectively. But, application of P and N was alone no any significant effect on the fertility status of the soil after crop harvest. Soil bulk density was reduced and porosity was increased in response to the combined application of farm yard manure, N and P at the rates of 10t FYM ha-1+ 111 kg N ha-1+ 46 kg P2O5 ha-1. Economic analysis also revealed that the highest net returns of 102878.18 Birr ha-1 was obtained in response to the combined application of farm yard manure , N and P at the rates of 10 t FYM ha-1+111 kg N ha-1+92 kg P2O5 ha-1 but the lowest net return was obtained from the control plot. In conclusion, application of farm yard manure with , N and P not only significantly improved the fertility status of the soil, but also productivity and profitability of the crop
