Effects of Plant Residue and Fertilizer on Nitrogen Uptake, Grain Yield of Wheat and Soil Organic Matter in Ahvaz*

Crop residues are vital organic resources and their extensive use in management for sustainable agriculture is widely recommended. Nitrogen is an important element for wheat production. This study examined the effects of different wheat straw and nitrogen fertilizer levels on yield, N uptake and soil organic matter. The experiment was conducted in two years under Ahvaz climatic conditions. Treatments were laid out in a split plot, randomized complete block design with four replications. Main plot treatments were growing a plant (as green manure) with all wheat straw (a1, a5), growing a plant (as green manure) with previous crop residual after removing of percentage straw from the field (a2, a7), mixed the whole straw with soil (a3), mixed wheat crop residues after taking out straw from the field (a4), burning the plant residue after harvested as traditional farming system (a6), and removing the whole residual of previous crop (a8). These preplanting operations were combined with three levels of chemical fertilizers; i. e. b1 for high grain yield potential, b2 for medium, and b3 for commonly harvested grain yield. Combined analysis of variance of two years showed that the effect of plant residue on soil organic matter was significant. Residue burned with 0. 632 percent the lowest and the highest was 0. 798 for a1. Main effect and interaction of treatments were not significant on soil nitrogen before top dressing on every year. Grain yields of different combination on combined analysis of variance was not significant. The higher yields were obtained from following combinations: a1b1، a3b2، a4b1، a4b2، a6b2، a7b1 and a7b2 with 5. 215, 4. 868, 5. 138, 5. 06, 4. 895, 5. 719 and 5. 011 kg/ ha yield respectively.