Effect of Different Levels of N.P.K. 15:15:15 Fertilizer Application on the Yield of Sweet Potato (Ipomea Batatas) in South-South Nigeria

This research was carried in Delta state Polytechnic School of Agriculture teaching farm in Delta state Polytechnic Ozoro in Isoko North local government area of delta state, Nigeria. There are different levels of fertilizer application suggested by various authorities. The need to elevate the effect of different levels of fertilizer application on the yield of sweet potato necessitated the study. Eighty vines of sweet potatoes collected from nearby farm were planted in complete randomized block design which was replicated three times. At establishment, twenty vines were dressed with 4.6kg fertilizer, another twenty 3.0kg, another twenty 7.4kg while the remaining twenty served as control. The parameters collected were subjected to analysis of variance (ANOVA). The results shows that (table 2) potato treated with 7.4kg fertilizer had more leaves of 127, 145.3, 177.7, and 184.7 as against 63, 83.3, 105.3, 127, and 83, 108.3, 134.3, and 162.0 for 3kg and 4.6kg respectively whereas the control had 28.7, 40.2, 58.6, and 67.3. Table (3) shows that Potato 7.4kgfertilizer had better length of vine of 66.1, 69.8, 81.2, 96.9 and 64.8, 70.1, 95.1 and 113.2 for 3.0 and 4.6kg respectively.Table (4) shows that 7.4kg treatment had superior weight of tuber of 114.38 as against 53.17, 80.26 and 34.11 for 3kg, 4.6kg and control respectively. Conclusively, sweet potatoes treated with 7.4kg fertilizer performed better in terms of number of leaves, vine length and weight of tubers at harvest. However there was significant difference among the treatment. It is therefore recommended that 7.4kg should be applied per stand so as to improve yield of potato and profit of the farmers.