No adverse effect of moderate stubble grazing on soil quality and organic carbon pool in dryland wheat agro-ecosystems

Stubble grazing by livestock in post-harvest wheat fields is a common practice. Current knowledge usually shows that grazing has negative effects on soil quality. Therefore, here, we studied the stubble grazing impact on soil quality and crop yields of continuous wheat croplands in the semi-arid northern Negev of Israel. These croplands have experienced the same stubble residue management, meaning, moderate grazing or entire retention, for 18 consecutive years. Cropland soils were also compared with soils of natural lands. Vegetation and 0-10 cm depth soils were sampled in 2013. Results reveal that overall soil quality was generally similar between the two wheat treatments. Moreover, results show that soil under stubble grazing treatment has greater carbon pool index and carbon management index than soil under stubble retention treatment. These findings suggest that the disturbance of soil organic carbon pool is smaller for stubble grazing, contrary to current knowledge. We propose a conceptual model to explain such findings.