Effect of Soil Tillage Method and Wheat (Triticum aestivum L.) Residue Management on Corn (Zea mays L.) Yield, Soil Properties, and Earthworm Population

Soil tillage method and plant residue management are two important agricultural practices which affect soil properties, fauna population and crop production. A 3-year field experiment was conducted to evaluate the effects of tillage methods (conventional tillage (CT), reduced tillage (RT), and No-Till (NT)) and wheat residue management (residue removal and retention) on earthworm population, infiltration process, organic carbon (OC), and corn yield at Zarghan, Fars province. The experimental design was a split-plot with three replications. The highest kernel yield (14447 kg ha-1) and harvest index (36.82%) of corn were obtained by RT and CT methods when residue returned, respectively. Applying RT method accompanied by keeping residue increased corn yield up to 30% compared to NT method. Organic carbon decreased by CT method and residue removal at 15 and 12% in the soil depth ranges of 0-10 and 10-20 cm compared to conservation tillage, respectively. The highest water infiltration process into the soil was achieved by RT and CT methods compared to NT method when residue returned. The highest earthworm population was obtained by NT method and residue retention, while earthworm population decreased by CT method and residue removal at 38.5 and 50% compared to RT and NT methods, respectively. It is concluded that, to grantee the corn yield potential and improve earthworm activity and soil fertility under wheat-corn rotation, adopting RT method accompanied by keeping wheat residue (standing residue with a height of 30 cm), is recommended.