Long-Term Effects of Different Tillage Methods and Crop Rotation on Soil Organic Carbon Storage

Fulfillment of a suitable tillage methods and crop rotation are two important management factors that can affect soil physical and chemical properties. This investigation was carried out to test the long-term effects of different tillage methods and crop rotation on physical and chemical properties of soil, based on a factorial and completely randomized block experiment with three replications at Mahidasht Agricultural Research Station for 5 years. The experimental variables included three tillage methods (no-tillage, chisel, and moldboard) and three different rotations (wheat-corn, wheat-canola, and wheat-safflower). In this project, in order to examine and determine the changes created in soil organic carbon pool, soil samples were taken from two layers: 0-15 and 15-30 cm. Soil bulk density and organic matter were measured. The result showed that the tillage treatments in the first years did not have significant differences, but in the later years, the tillage factor was significant. Indeed, in the last study years and also in the overall five-year period, using the no-tillage method was much preferable due to improving the soil organic matter pool by about 5.1 ton per hectare. Application of chisel in tillage system decreased soil organic carbon storage by about 1.5 ton per hectare. Also, wheat-canola rotation was suitable more than the other rotations. Therefore, adoption of no-tillage together with wheat-canola rotation is recommended for the area in the long term.