Corn Yield and Quality and Weed Growth Under Different Nitrogen Levels by Application of Legume and Non-Legume Green Manures

In order to study the effects of green manures and various levels of nitrogen fertilizer on yield and quality of corn (Zea mays L.) and weed growth، an experiment was conducted in the Research Farm of Agricultural and Natural Resources Faculty، Razi University as split plot based on a randomized complete block design with three replications in the 90-91 growing season. The main factor was green manure and its incorporation time including rye incorporated in March، rye incorporated in April، common vetch incorporated in March، common vetch incorporated in April، mixed (rye + commom vetch) incorporated in March، mixed incorporated in April and control (without green manure). The sub factor was nitrogen fertilizer as urea with three levels including 0 (no fertilizer)، 200 kg. ha-1 (the 50% of the recommended amount) and 400 kg. ha-1 (the 100% the recommended amount). Results indicated that green manure and nitrogen treatments had significant impacts on yield and yield components، grain protein content and weed biomass. The highest grain yield belonged to the April-incorporated vetch by 12124. 7 kg. ha-1 and the lowest one was obtained in control (without green manure) by 9185. 6 kg. ha-1. Among the nitrogen fertilizer levels، the 100% of the recommended amount with 11253. 8 kg. ha-1 and no fertilizer treatment with 9041. 3 kg. ha-1 showed the highest and the lowest yields، respectively. Green manure and nitrogen fertilizer also influenced weed growth in corn field as the lowest weed biomass was produced by mixed treatment incorporated in April without nitrogen fertilizer.