Soil aggregation is an essential indicator of soil health and productivity. The physical component of soil is characterized by different aggregate-size classes, ranging from micro- to macro-aggregates. The different soil aggregate-size classes demonstrate distinct physical, chemical, and biological properties, including the contents of organic carbon. The OC contents of soil determines the sustainability and resilience of the agroecosystems and are linked with multiple parameters of soil health and crop productivity. The positive impact of cover crops on the OC contents of soil aggregates should nevertheless suggest their role in soil carbon storage because the decomposition rates of carbon are decreased with the size of different aggregate size classes. This study aimed to demonstrate that cover crop type and diversity will improve OC contents of different soil aggregate-size classes.