RESPONSE OF MAIZE VARIETIES TO N-FERTILIZER RATES UNDER DRAINAGE CONDITIONS IN CLAY SOIL.

Abstract

A field experiment was conducted at the Experimental Farm of Sakha Agric. Res. Station during the two summer growing seasons (2012 and 2013), to evaluate the effect of distance from drain line (1/4 and 1/2 distance from drain line) and applied N-fertilizer rate (90, 120 and 150 kg N/fed) on yield and yield components as well as N-content of two maize hybrids (single pioneer hybrid No. 10 (V2) and ternary hybrid No 329 (V1)) in clay soils. The tile lines were spaced to simulate a 20 m spacing and 1.2 m depth with a slope of 0.1%. Data showed that: Water table depths were increased with increasing time after irrigation. Water table depth near the drains was higher than in midway between drains. Soil bulk density was lower near the drain and gradually increased towards the midway between drains. Decreasing distance from drain line from L/2 to L/4 resulted in a significant increase in yield and yield components of maize crop as well as N-content (kg/fed.) and protein percentage in both seasons. Maize grains yield, 100 grains weight, ear diameter and Plant height increased with increasing rate of N-fertilization. The values of maize grain yield were 25.71, 27.66 and 29.68 ardab/fed in the first season and 26.23, 28.62 and 30.72 ardab/fed in the second season for 90, 120 and 150 kgN/fed., respectively. The corresponding values of protein percentage were 6.01, 11.68 and 15. 55 % in the first season and 5.94, 11.54 and 15.52 % in the second season, respectively. Data showed that V2 resulted in a significant increase in the grain yield, 100 grain weight and Plant height of maize crop. The combination between distance from drain line and 150 kgN/fed resulted in a high yield and yield components as well as N-content of maize crop. Maize varieties resulted in somewhat differences in the grain yield, 100 grains weight, ear diameter and Plant height as well as N-content and protein percentage of maize crop in both seasons with every N-fertilization. The highest values of grains yield, 100 grains weight, Ear diameter and Plant height as well as N-content and protein percentage of maize crop were obtained with combination between L/4, 150 kgN/fed and V2 while, the lowest values were obtained with interaction of L/2, 90 kgN/fed and V1 in both studied seasons. The obtained results revealed also, that 20 m drains spacing in clay soils is not the proper but may be economic. In addition, distance from drain line must be taken into consideration when distributing fertilizer treatments and their replicates in fertilization experiments to obtain reliable results.