Effects of rotation and crop residue management on nitrogen application rate in corn planting and some of the soil chemical properties in khouzestan.

Recent alarms worldwide and also in iran, in relation to environmental problems and instability of agricultural production has caused those agronomic practices, such as determining the appropriate previous crop, management of crop residues and the optimal use of fertilizers, especially nitrogen, particular attention should be. So, in order to study the effect of rotation (previous crops) and crop residue management on nitrogen application rate in corn (zea mays.L cv. SC704) planting and some of the soil chemical properties, this expreiment was conducted in 2008-2012 at Safiabad Agricultural Research Center, Dezful. The experiment was as split- factorial in randomized complete block design with 16 treatments and three replications.Two levels of rotation (canola-corn and wheat-corn) were assigned to main plots and nitrogen at four levels (0,100,200 and 300 kg ha-1) and crop residue at two levels (maintaining all of crop residue and complete removal of crop residue) as factorial were randimized in sub-plots. The results showed that the main effect of rotation on corn grain and biological yields and other traits were not significant. The main effect of nitrogen application had significant effects on corn grain and biological yields, 1000-grain weight, harvest index, nutrient uptake, nitrogen utilization efficiency and organic carbon and available phosphorus and potassium after harvesting, so that with nitrogen application mentioned indices increased. The main effect of crop residue on studied traits was significant except harvest index and nitrogen utilization efficiency. The interaction effects of nitrogen and crop residue management on the corn grain and biological yields, 1000-grain weight, nutrient uptake rates and nitrogen utilization efficiency were significant. In general, the highest yields of grain (7724kg ha-1) and biological (14273kg ha-1) were obtained from maintaining all of crop residue in conjunction with nitrogen application (200 kg ha-1). Therefore, regarding to the condition of this experiment, application of 200 kg N ha-1 in combination with maintaining of residue is recommended for corn production in this region. Key words: Corn, Nutrient, Organic carbon, Plant residue, Rotation