Effects of Integrated Use of Lime and Nitrogen Fertilizer Rate on Maize (<i>Zea mays</i> l.) Crop and Its Profitability on Nitisols, Ethiopia

In the highlands of Ethiopia soil acidity is the limiting factor for crop production due to leaching effects of basic cations, nutrient loss by erosion, crop residue removal from farmland and other human induced factors. This study was carried out at Burie district to determine the effect of integrated use of lime and nitrogen fertilizer rate on yield and yield components of Maize in acidic nitisols. The treatments include lime (0 and 0.5 t ha-1) and nitrogen fertilizer (0, 100, 200, 300, and 400 kg ha-1). To fulfill the law of minimum, 200 kg ha-1 die ammonium phosphate (DAP) which is recommended rate of NPS (19% N, 38% P2O5 and 7% S) fertilizer was used uniformly to all plots at the time of planting. The maize variety BH-661 was used as a test crop. The experiment was laid out in a randomized complete block design (RCBD) with ten treatments replicated three times. Yield and yield components of maize were collected and analyzed. The analysis of variance result revealed that, interaction effect of lime and N fertilizer reduced the tasseling period (88 days in the application of 0.5 t ha-1 lime with 100 kg ha-1 N to 85 days in combined use of 0.5 t ha-1 lime with 400 kg ha-1 N) and silking period from 91 days to 88 days. Grain yield was highly and positively correlated with AGDB (r=0.996) and HI (r=0.987). Grain yield of maize in the study area was increased from 5,550 kg ha-1 to 6,410.20 kg ha -1 (adjusted yield). Yield increment was 13.42%. The average maize yield in the region was 3,780 kg ha-1 but in the study area the adjusted yield was 6,410.20 kg ha-1. As compared with regional maize yield it was increased by 40.3%. However, yield was highly and negatively correlated with DT (r=-0.957) and DS (r=-0.925). The maximum agronomic use efficiency of (3.76%) was from Treatment 10 (0.5 t ha-1 lime with 400 kg ha-1 N) than Treatment 7 (0.5 t ha-1 lime with 100 kg ha-1 N) of (3.16%). Based on the economic analysis, the net benefit value 47,701.04 Ethiopian Birr. Therefore, integrated application of 0.5 t ha-1 lime and 300 kg ha-1 Nitrogen fertilizer is economically reasonable and recommended to the farmers.