SOIL FERTILITY STATUS AND RESPONSE OF MAIZE (Zea mays L.) TO NPS AND DAP FERTILIZERS RATES IN BAKO TIBE DISTRICT, WESTERN ETHIOPIA

Low soil fertility and lack of site specific fertilizer recommendation to replenish declining soil fertility have been the critical challenges to boost maize production in Ethiopia. This study was conducted during 2017 cropping season in Bako Tibe district of west Shewa Zone to assess soil fertility of study area. One hundred geo-referenced soil samples were collected from 1 km x 1 km sub grid generated within 10 km x 10 km main grid. Field experiment was also conducted in this grid to determine response of maize crop to NPS and DAP fertilizers rates. The experiment was laid out in Randomized Complete Block Design with three replications and plot size of 5.1 m x 4.5 m. The treatments were control, 50% recommended rate (RC) of DAP, 50% RC. NPS, 100% RC.DAP, 100% RC.NPS, 125% RC.DAP, 125% RC.NPS, 150% RC.DAP, 150% RC.NPS, 175% RC. DAP and 175% RC.NPS fertilizer. The soil samples were analyzed for pH, N, OC, P, K, S, Mg, Ca, Zn, Fe, B, and Mn. Soil and plant collected during harvesting were also analyzed for N, P and S. Total N (0.02-0.07%), SOM (1.12-2%) and available P (1.2 -20.3 mg kg-1) of the soil were varied from very low to low rates. Extractable S (4.38 -9.75), available K (37.12-146 mg kg-1) and CEC (6.2-23 cmol+ kg-1) of the soil were ranged from low to medium range. The soil pH (5.2-6.62) was ranged from moderately to slightly acidic in soil reaction. Available Fe (58.1-199.9 mg kg-1), Mn (14.4 - 88.2 mg kg-1) and Zn (0.4 -1.7 mg kg-1 were sufficient whereas available B (0.01 - 0.05 mg kg-1) content of the soil was deficient. The results of the experiment indicate significant effect of NPS and DAP fertilizer on maize yield and yield components. The highest grain yield 8660 kg ha -1and the next maximum yield 8540 kg ha-1 were obtained at 150% recommended rate of DAP and 175% recommended rate of NPS fertilizer respectively. Addition of sulfur nutrient did not resulted in significant yield increment over sulfur omitted NP (DAP) rates. Application of 150% recommended DAP and NPS fertilizer provide the highest yield and net benefit for maize producers. Therefore 150% recommended DAP and NPS fertilizers rate are recommended for study area. Soil fertility management practices that can improve pH, SOM, CEC, N P K, S and B should be adopted for better production of maize in the study Area.