Antar, A. S. ( 2013). Nitrate leaching losses into field drain tiles as affected by land leveling and N-fertilizer under wheat crop. J. Agric. Res. Kafr El-Sheikh Univ., 39 (4), 616- 635.
Abstract: A field experiment was conducted at the Experimental Farm of Sakha Agric. Res. Station, during the winter seasons (2011/2012 and 2012/2013), to evaluate the effect of land leveling and applied N-fertilizer rates on nitrate leaching losses into field drains tiles in clay soils, as well as yields and uptake of wheat plant. Results indicated that the drain discharge decreased with time especially in the first few days after irrigation. Drain discharge were higher with traditional land leveling (from 0.3 to 9.1 mm day-1) than that of laser land leveling (from 0.2 to 5.6 mm day-1). Cumulative discharge was higher with traditional than with laser land leveling. NO3- content of the soil ranged from 29.5 to 38.5 ppm before cultivation, and from 54.4 to 79.5 ppm after fertilizer application. The contents of NO3- were reduced at the end of the seasons (20.4 to 40.8 ppm), and was higher under laser than under traditional land leveling. It was increased with the increasing N-fertilizer rate from 75 to 125% of the recommended N. The average values of NO3- content of the soil after fertilization were 62.3, 64.0 and 67.1 ppm with traditional land leveling and 67.5, 70.1 and 76.4 ppm with laser land leveling under N-fertilizer rate of 75, 100 and 125 % of the recommended N, respectively. At the end of the seasons, the mean content of NO3- were 26.2, 30.6 and 34.7 ppm with traditional leveling and 33.2, 35.8 and 39.6 ppm with laser land leveling under rates of 75, 100 and 125 %, respectively. NO3- concentration in drainage water was increased after fertilizer application and reduced with time. The high concentrations of Nitrate in drainage water were found with the high rate of N-fertilizer. Land leveling had no clear effect on NO3- concentration of drainage water. Nitrogen losses were paralleled to the cumulative discharge and N-fertilizers rate results. The highest values of nitrogen losses were found with traditional leveling and high rate of N-fertilizers. Where the addition of 125%N rate caused increase of NO3-, NO3--N and total fertilizer losses by 6.55, 1.48 and 3.22 kg fed-1, respectively than 75%N and about 3.52, 0.79 and 1.73 kg fed-1, respectively than100%N under traditional levelling. And were 4.21, 0.96 and 2.07 kg fed-1 than 75%N and about 2.87, 0.65 and 1.41 kg fed-1 than100%N, respectively under laser levelling. The losses percentages from the used nitrogen fertilizer were 6.99, 6.16 and 5.77 % with traditional land levelling and 5.24, 4.33 and 4.15 % with laser land levelling under N-fertilizer rate of 75, 100 and 125 % of the recommended N, respectively. Data showed significant differences in yields and N-uptake of wheat between laser and traditional leveling, as well as between N-fertilizer rate of 75N% and both 100N% or 125N % with no significant difference between 100N% and 125N % from the recommended. Laser land leveling caused increase of grain yield than traditional leveling by 227, 191 and 201 kg fed-1 in the first season and by 182, 77 and 124 kg fed-1 in the second season for 75, 100, and 125% from the recommended N, respectively. Also, laser land leveling caused increase of wheat straw yield than traditional leveling by 14.46, 5.26 and 6.29 % in the first season and by 10.42, 3.85 and 4.23% in the second season for the treatments of 75, 100 and 125% from the recommended N, respectively. N-uptake were higher under laser land leveling than under traditional land leveling by 7.01, 6.96 and 9.21 % for grain and 15.02, 7.66 and 6.60 % for straw with N-fertilizer rate of 75, 100 and 125 % from the recommended N, respectively.
Keywords: (Drainage, N-fertilizer, Land leveling, Nitrate leaching, Wheat, N-uptake.)
