Effect of Blended (NPSB) Fertilizer Rates and Plant Population on Yield and Yield Components of Maize (Zea mays L.) at Bako, Oromia National Regional State, Ethiopia

Maize (Zea mays L.) is the major cereal crop in Ethiopia and plays a crucial role in ensuring food security. However, its productivity is constrained by a number of problems, among which use of high or low plant population and poor soil fertility management are the most critical once. Therefore, a field experiment was undertaken to determine the optimal NPSB fertilizer rate and plant population for maize at Bako. The experiment was laid out in split plot design distributing three levels of plant population [53,333 plants ha -1 (25 x75 cm), 66,666 plants ha -1 (60x25cm) and 76923 plants ha -1 (65x20cm)] in the main plots and five levels of NPSB fertilizer rates (0,100,150,200 and 250 kg NPSB ha -1 ) and recommended NP rates as sub-plots. The interaction of plant population and NPSB rates influenced significantly (P<5 %) leaf area index, number of cobs plot -1 , number of kernel cob -1 , dry biomass and thousand kernel weight. The highest leaf area index 6.661 was recorded on the combination of 66,666 plants ha -1 with 200 kg NPSB fertilizer rate. The highest number of cob plot -1 (115.3) and dry biomass yield 28,299 kg ha -1 were recorded from 66,666 plant ha -1 with 150 kg NPSB ha -1 , and 53,333 plant ha -1 with standard check 92/69 kg NP ha -1 , respectively. The highest grain yield 9954 kg ha -1 with net profit of 76,038 Birr with marginal rate of return 598% was obtained from 150 kg NPSB ha -1 with 66666 plants ha -1 (60 cmx25 cm). Therefore, application of 150 kg NPSB ha -1 with 66666 plants ha -1 for farmers in the study area and with similar agro-ecology can use and can improve maize productivity. However, the experiment need to be further verified in multi-locations for better usage at different agro-ecologies. The analysis of variance that to silking by different NPSB fertilizer rates (P<0.05). The longest number of days to silking (89 days) was recorded on the treatment of control. All treatments that with different level of fertilizer the silking of maize and all were statistically par that about 85-86 days. These results are in agreement ha plant ha ha -1 fertilizer ha -1 plants -1 92/69 NP ha -1 with 53,333 plants ha -1 , 150 kg NPSB ha - 1 with 53,333 plants ha -1 , 200 kg NPSB ha -1 with 53,333 plants ha -1 , 100 kg NPSB ha -1 with 66,666plants ha -1 , 250kg NPSB ha -1 with 66,666 plants ha -1 , 200 kg NPSB ha -1 with 76,923 plants ha -1 and kg NPSB ha -1 with 76,923 plants ha -1 and gave 9409 kg ha -1 , 9167 kg ha -1 , ha -1 , ha -1 , ha -1 , 9037 kg ha -1 and 9660 kg ha -1 , respectively. The plots received 76,923 plant ha -1 with 92/69 kg NP ha -1 and 76,923 plant ha -1 with 100 kg NPSB ha -1 also produced statistically similar grain yields 9803 kg ha -1 and 9908 kg ha -1 , respectively. This study indicated that maize grain yield depends on the plant and NPSB fertilizer applied per unit