Effect of irrigation intervals and nitrogen rates on forage sorghum under North Sinai conditions
2009
El-Sarag, E.I. | Abuo- Hashem, G.M.
Irrigation intervals (3, 5 and 8 days) and nitrogen fertilizer rates (45, 60, 75 and 90 kg N fed-) on forage sorghum (Sorghum bicolor) were studied. Nitrogen fertilizer (Urea 46%) was applied in three equal doses (20 days after emergence, after the 1st and the 2nd cuts). The experimental design was randomized complete block (RCBD) in a split plot design with three replications. The main plots were chosen for irrigation intervals, the sub-plots were devoted for nitrogen rates. Drip irrigation system was used with saline ground water (ranged between 3500 to 4600 ppm) pumped from a local well. Three cuts were taken throughout the growth season at 60, 105 and 136 days after sowing. All studied growth criteria had the highest values with irrigation every 3 days at all cuts in both seasons and combined analysis. The same trend was found with fresh, dry and protein yield. However, the highest means of crude protein was recorded with irrigation every 8 days at all cut except the third one, which irrigation every 5 days gave the highest crude protein in both seasons and combined analysis. Increasing nitrogen fertilizer rate from 45 to 90 kg N fed- increased all studied growth characters at the three cuts and over them in both seasons and combined analysis. Also, the maximum forage fresh, dry and protein yi0d were achieved when 90 kg N fed- was applies.
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