Soil Organic Matter Changes and Crop Yield in Conservation and Conventional Tillage Systems under Wheat-Corn Rotation in Zarghan Region (Fars Province, Iran)

In order to evaluate the effects of tillage methods on soil organic matter (OM) content and crop yield, a field experiment was conducted under wheat-corn rotation based on split-plot design in three replications at Zarghan, Fars province. Results showed that the reduction of soil tillage operations accompanied by keeping crop residue can be improved OM content compared to conventional tillage (CT) methods. At a soil depth range of 0-10 cm, the OM content increased two % by applying reduced tillage (RT) method and residue retention compared to CT method. In deeper soil layers, OM content enhanced one % by CT method and residue retention compared to RT method. Results showed that grain yield of wheat increased 24.5% by applying RT method and corn residue retention compared to CT method. While, wheat yield decreased 48% by applying No-Till (NT) method compared to RT method. Furthermore, applying NT method and corn residue retention increased wheat yield by 21% compared to crop residue removal. In wheat residue retention, results showed that kernel yield of corn increased by 34% under CT and RT methods compared to NT method. In contrast, keeping wheat residue accompanied by NT method application can be increased kernel yield of corn at 5.5% compared to crop residue removal. It is concluded that, to maintain the crop yield potential and increase OM content under a consecutive corn-wheat rotation in arid and semi-arid regions, adopting RT method accompanied by keeping crop residue (standing residue with a height of 30 cm), is recommended.