EFFECT OF LEVEL AND TIME OF NITROGEN FERTILIZER APPLICATION ON GROWTH, YIELD AND YIELD COMPONENTS OF MAIZE (Zea mays L.) AT ARBA MINCH, SOUTHERN ETHIOPIA

Abstract

Crop nutrient utilization efficiency could be enhanced with optimum level and right time of application. A field experiment was conducted at Arba Minch Southern Ethiopia on maize hybrid variety, BH 140, during 2016 cropping to determine the effect of level and time of nitrogen fertilizer application on growth, yield, yield components and economics of maize cultivation. The experiment consisted of six levels of nitrogen (N) (0, 23,46,69,92 and 115 kg N ha -1 ) and four times of N application (½ dose at sowing + ½ dose of N at 40 days after sowing; ½ dose of N at 40 days after sowing + ½ dose of N at tasseling, ¼ dose of N at sowing + ½ dose of N at 40 days after sowing + ¼ dose of N at tasseling, and full dose of N at 40 days after sowing). The experiment was laid out in Randomized Complete Block Design with three replications. Data was collected on days to tasseling, days to silking, days to maturity, leaf area index, plant height, number ear per plant, ear height, dry matter, ear length, number of kernels per ear, hundred kernels weight, grain yield and harvest index. The effect of N level was highly significant (P<0.05) for phenological parameters, growth parameters as well as yield and yield components. As for time of N application, it had significant effect on days to tasseling, leaf area index, days to maturity, plant height, ear length, number of ear per plant, hundred kernels weight and harvest index. The interaction between level and time of nitrogen application was significant for days to silking, number of kernels per ear and grain yield. High values of all growth and yield parameters including grain yield, were obtained when N application was split as ¼ dose at sowing + ½ dose at 40 days after sowing + ¼ dose at tasseling. The highest grain yield (9036.7 kg ha-1) was recorded the combination 69 kg N ha -1 with three split application, while the lower grain yield (4316 kg ha-1 ) was recorded from the control treatment. Grain yield showed highly significant and positive linear correlations with all the parameters except days to maturity. The highest economic benefit (51,843 Birr ha -1 ) and higher acceptable (2018%) were obtained from applying 69 kg N ha -1 in three splits as ¼ dose at sowing + ½ dose at 40 days after sowing + ¼ dose at tasseling. Therefore, it is concluded that split application of 69 kg N ha -1 (¼ dose at sowing + ½ dose at 40 days after sowing + ¼ dose at tasseling) could be appropriate to attain higher and economical maize production in Arba Minch. Thus, applying 69 kg N ha-1 with three split application is promising to come to the conclusion and the study is required to be repeated for one more season.