Evaluation of FYM and Inorganic NP Fertilizers on Yield Performance of Sweet Potato Ipomoea batatas (L.) Lam in Debub Ari District, Southwestern Ethiopia

Lack of appropriate recommendation rates of fertilizers is one of the major problems limiting yield production. A study was conducted to evaluate the effect of FYM and inorganic NP fertilizers on tuberous root yield and yield related parameters of sweet potato at Jinka Agricultural Research Center Station. The treatment consisted of three levels of N (0, 23 and 46 kg ha-1), three levels of P (0, 20 and 40 kg ha-1) and three levels of FYM (0, 2.5 and 5 t ha-1). The experiment was laid out as a Randomized Complete Block Design in a factorial arrangement and replicated three times. Analysis of the results showed that the main effects of nitrogen (P < 0.05), phosphorous (P < 0.05) and farm yard manure (P < 0.05) showed significant difference on total tuber yield and fresh biomass but dry matter was non-significantly affected by the main effects of nitrogen (P < 0.05), phosphorous (P < 0.05) and farm yard manure (P < 0.05). The interaction effects of N (P < 0.05), P (P < 0.05) and farm yard manure (P < 0.05) showed significant difference on total tuber yield, fresh biomass and dry matter. Soil samples collected from the experimental field before treatment application showed sandy clay in texture, moderately acidic in reaction, very low in total nitrogen, low in available P, medium in organic carbon, and low cation exchange capacity. Maximum total tuber yield was recorded at the combined application of N, P and fam yard manure at the rates of 46 kg N ha-1, 92 kg P2O5 ha-1 and 5 t FYM, respectively which was in statistical at parity with the application of 46 kg N ha-1, 92 kg P2O5 ha-1 and 2.5t FYM whereas the minimum was obtained for the combined application of nil rates of all fertilizers. A maximum net return of 226477.6 ETB was obtained from plots receiving treatments of 46 kg N ha-1, 92 kg P2O5 ha-1 and 5t FYM compared to the minimum net benefit (82404.9 ETB) from the control plots. However, the application of 46 kg N ha-1, 92 kg P2O5 ha-1 and 2.5t FYM was also at par net benefit (223588.3 Eth-Birr) with those treatment. So, to minimize production cost and due to environmental friendly, combined application of 46 kg N ha-1, 92 kg P2O5 ha-1 and 2.5t FYM is recommended. Sweet potato growers can also use 46 kg N ha-1, 92 kg P2O5 ha-1 and 5t FYM as an alternative option for long term productivity of the soil.