Effect of Conservation and Conventional Tillage Methods on Soil Macro-Fauna Population in Wheat-Corn Rotation in Zarghan Region

Soil management changes can have either negative or positive impacts on crop production, depending on many factors including region, rotation, soil properties, tillage intensity, and at the same time, alter soil fauna diversity. Little attention has been paid to the response of soil fauna to changes in soil tillage methods. Results showed that soil fauna groups and natural enemies affected by conservation tillage resulting in changed soil fertility and small habitats accessibility. Thus, the aim of this study was to investigate the effect of conservation and conventional tillage on soil macro-fauna communities and species diversity in wheat (Triticum aestivum L.)-corn (Zea mays L.) rotation.

In order to evaluate the effects of soil tillage methods (conventional tillage (CT), reduced tillage (RT), and No-Till (NT)) and crop residue (residue returned and exported) on soil macro-fauna in a wheat-corn rotation, a 1-year field experiment (two growing seasons) was conducted in 2016-2017 based on split-plot design in three replications, in Zarghan, Fars province. Sampling was done by pitfall traps and species diversity indices were measured using Past software. Data were collected and performed with the function of split plot design using SAS 9.3 software. Means were separated using Duncan’s Multiple Range test at 5% probability level.

Results showed that soil macro-fauna abundance increased up to 6% in corn cultivation compared to wheat, when plant residue returned. Soil macro-fauna abundance was positively affected by conservation tillage and residue retention, so that applying RT and NT systems increased soil macro-fauna compared to CT system approximately one time. Shannon index in NT, RT and CT systems were 1.88, 1.91 and 1.92, while Simpson and Berger-parker indices were 0.83, 0.84, 0.85 and 0.31, 0.28, 0.25, respectively, when residue returned. The highest Hill index (0.68 and 0.71) was obtained by CT system and plant residue removing in wheat and corn, respectively.

Although there is a wide range of responses among different species, most macro-fauna groups have greater abundance in RT system and residue retention compared to CT and NT systems due to increasing and creating diverse habitats on the soil as a result of plant residue retention and reducing soil tillage operations. Overall, greater knowledge of different soil tillage methods and residue management effects on soil macro-fauna groups will allow for a better understanding of interactions between soil macro-fauna and natural enemies with crops and would aid the development of pest management strategies as components of sustainable agricultural programs.