The Effect of Poultry manure and Urea on Agronomic Characters of Forage Maize Under Drought Stress Conditions

In order to evaluate the effects of drought stress, poultry litter and urea fertilizers on agronomic properties of forage maize (cv. SC704), a spilt-plot experiment arranged in randomized complete blocks design was conducted with four replications at the research station of Shahrekord University in 2009. The main plots consisted of irrigation treatments at two levels, normal irrigation and irrigation stop at pollination stage for two weeks. Sub-plots were assigned to fertilizer treatments with three levels of urea fertilizer (F1=217, F2=435 and F3=652 kg ha-1), and three levels of poultry litter (F4=5.28, F5=10.57 and F6=15.86 Mg ha-1) and F0 as the control (no fertilizer) treatment. Results showed that drought stress had a significant effect on stem and ear fresh weights, ear diameter and fresh forage yield, but not on green and yellow leaf numbers, leaf area index, tasselling and silking creation, anthesis–silking interval, plant height, stem diameter, ear length and leaf fresh weight. The effects of fertilizer treatments were significant on all the measured characters with the exception of leaf numbers. The application of nitrogen resulted in an increase in forage yield, most likely due to increased leaf area index, leaves, stem and cob weights, length and diameter of cob, stem diameter, plant height and decreased anthesis–silking interval in N-fertilized treatments. Poultry litter and urea fertilizer × drought stress interactions were observed for leaf area index, leaf and stem fresh weights. The highest fresh forage yield (101 Mg ha-1) was observed in the normal irrigation and 15.86 t ha-1of poultry litter treatments that significantly differed from other treatments. However, if a large quantity of poultry litter is unavailable, 10.57 t ha-1 of this manure that had no significant differences as compared with 652 kg ha-1 of urea fertilizer, would lead to an optimum yield.