The Effect of Crop Residue on Organic Carbon and Fertility of the Soil in Wheat-Corn Rotation

Addition of plant residues is an effective strategy for increasing soil nutrients, improving their use efficiency, providing better conditions for root growth and sustainable crop production. A field experiment was conducted to assess the effects of incorporation of varying rates of crop residue on the soil organic carbon and nutrients status at 0-10, and 10-20 cm soil depth, in a wheat-corn rotation under conventional tillage system. The field experiment was performed as a factorial and in the form of completely randomized block design with four replications in the farm of agricultural and natural resources college of University of Tehran for two growing years. The treatments included incorporation of five levels of crop residues (100, 75, 50, 25 and 0%) which were added to the soil in two steps, following wheat and corn rotation. The results of this study indicated a significant effect of crop residues on the measured properties. Among the crop residues treatments, the 100% level showed the greatest increase of organic carbon (38.4%), available phosphorus (34%) and potassium (47.6%), as well as iron (27%), manganese (30.3%), copper (39.5%) and zinc (62%), as compared to 0% residue treatment. The 25% residue treatment showed the lowest value for the studied properties, compared to other residues treatments. Available phosphorus, iron and zinc were significantly affected by depth and their values decreased with increasing depth from 0-10 to 10-20 cm.