EFFECT OF FARMYARD MANURE AND MINERAL NP FERTILIZERS ON YIELD RELATED TRAITS AND YIELD OF POTATO (Solanum tuberosum L.) AT AREKA, SOUTHERN ETHIOPIA

Abstract

Declining soil fertility is one of the major problems causing yield reduction in Ethiopia. Farmers at Areka apply both organic and inorganic fertilizers to overcome the problem and increase yield of potato. However, information on the application of farmyard manure and chemical fertilizer is inadequate to the area to increase the yield of potato crop. Therefore, an experiment was conducted at Areka, Southern Ethiopia during the 2016 cropping season with the objective of assessing the effect of farmyard manure and mineral NP fertilizers on yield related traits and yield of potato. There were twenty treatments comprising of four levels of FYM (0, 2.5, 5, 7.5 t ha-1) with five levels of combined mineral NP fertilizers [0, 25%, 50%, 75%, 100% of blanket recommended rates of NP(110 kg N ha-1 and 90 kg P2O5 ha-1)] in randomized complete block design in factorial arrangement with three replications. The improved potato variety “Belete” was used as a test crop. The results showed that the main effect of FYM and mineral NP fertilizers were significant (P<0.01) on tuber number per hill, tuber size category and tuber yield in tha-1.The highest marketable tuber number per hill (8.38), highest total tuber per hill (11.69) and highest large sized tuber (69.21%) were recorded from application of 7.5 FYM t ha-1 The highest marketable tuber number per hill(8.42),highest total tuber number per hill(11.67) and highest large sized tuber (68.79%) were recorded from application of 100% mineral NP fertilizers. There were significant interaction effect of FYM and mineral NP fertilizers on days to 50% flowering, days to maturity and plant height. The maximum total and marketable tuber yields of 35.11t ha-1, and 33.97 t ha-1recorded at the rate of 7.5 t ha-1 FYM respectively while the maximum total and marketable tuber yield of 37.97 t ha-1and 36.78 t ha-1respectively were obtained in response to the application of 100% blanket recommended mineral NP fertilizer rate . However, partial budget analysis indicated that application of 7.5 t ha-1 FYM and 75% of blanket recommended mineral NP fertilizers gave the optimum net benefit with the marginal rate of return 282.2%. It could, thus, be tentatively concluded that application of 7.5 t ha-1 FYM and 75% of blanket recommended mineral NP fertilizers resulted in optimum growth and yield of the crop