Effect of Conservation Tillage and Wheat Residue Management in Some Soil Properties and Grain Yield of Corn

In order to achieve sustainable agriculture, improving soil characteristics by proper residue management is necessary. The objective of this research was to comparethe effect of conservation tillage (reduced tillageand no tillage) and the effect of wheat residues management on some soil properties and corn yield. Tillage treatments included three levels of reduced tillage by disk, reduced tillage by combined machine, and no tillage (chisel packer). Wheat residue-management treatments consisted of removing the residue by burning (conventional method) and retention of 100%, 75% and 35% of residue. This experiment was performed as split block in randomized complete blockdesign with three replications. According to the results, the two reduced tillage treatments were in one statistical group and no tillage was in another, with the grain yield of 12370 kg/ha. Grain yield in reduced tillage using chisel packer was more than the yield of no tillage by 635 kg/ha. In the two methods of reduced tillage, the corn yield was more than the yield of no tillage by about 5%. Soil organic carbon and potassium (K) were affected by tillage method and residue, so that burning the residue treatment in all three tillage treatments had the least soil organic carbon (SOC) and the highest available phosphorus (P) and potassium (K). Interaction effect of tillage and residue management in year showed that, in the third year, burning of the wheat residue in reduced tillage condition had the highest available potassium in the soil.  In the third year of the experiment, soil organic carbon in the residue retention treatments increased by, respectively, 13%, 19%, and 19%. In the same year, reduced tillage by using chisel packer increased the soil organic carbon (SOC) about 8% by preserving the 75% of residue. Based on the results of this research, for the region of study, burning of the plant residues should be avoided and retention of 35-75% of residue and using reduced tillage methods is recommended.