Effect of tillage, water stress and nitrogen fertilizer on forage quality of maize in Karaj

To study the effect of nitrogen fertilizer and irrigation regimes on yield and some qualitative traits of forage maize cultivated under traditional and conservational tillage systems, an experiment was conducted in 2018 in split-split plot on randomized complete block design with three replications in University of Tehran. The effects of tillage as main factor in two levels (traditional and no-till), water stress as the sub-factor in three levels (30%, 60% and 90% of moisture requirement) and nitrogen fertilizer as a sub sub-factor at three levels (0%, 50% and 100% of the recommended rate) were studied on qualitative traits (DMD, WSC, CP, ADF, NDF, CF and Ash) and dry matter of maize plant. The results showed that the highest dry matter of maize (18.3 t ha-1) was obtained from no-water stress treatment under traditional tillage which was and the lowest (7.2 t ha-1) was observed in severe water stress under no-till condition. 100% nitrogen fertilizer treatment with no-water stress under traditional tillage produced the highest percentage of crude protein (12.22%)and non-nitrogen fertilizer and moderate water stress treatment under no-till resulted in the lowest crude protein (6.11%) . The highest (25.43%) and lowest (13.27%) percentage of acid detergent fiber in corn forage was obtained from 100% nitrogen fertilizer with severe water stress under conservation tillage and 100% nitrogen fertilizer with moderate water stress under no-till conditions, respectively. Agronomically, it seems that it is not possible to achieve the aims of no-till in short-term. In other words, conservation tillage will be effective after the transition stage. Also, increasing nitrogen content under water stress did not have a positive effect on forage quality.