Evaluation of soil organic matter dynamics under crop residue management using carbon-13 isotope

The use of nuclear techniques can be helpful in the selection and implementation of optimal agronomic practices as well as the provision of appropriate management strategies in soil and water conservation, achieving sustainable development goals. In this study, we investigated the effects of applying wheat and maize crop residue at five rates, including 0, 25, 50, 75, and 100 %, on the dynamics of soil particulate organic matter (POM) and its origin at depths of 0-10 and 10-20 cm under conventional tillage and no-tillage systems were aimed. For this purpose, the natural abundance of carbon-13 (δ13C) technique was used. The results showed that increasing residue rates in the conventional tillage system increased the amount of δ13C at two soil depths of 0-10 and 10-20 cm. In the no-tillage system, increasing residue rates led to an increase of δ13C only for the depth of 0-10 cm, and no significant differences were observed among residue treatments at a depth of 10-20 cm. In addition, the comparison of δ13C values ​​of soil and plant residues of wheat and corn confirmed that the main source of soil particulate organic matter originated from the wheat residue, indicating the more substantial effect of wheat residues on improving soil organic matter than maize.