Soil aggregates and associated carbon and nitrogen storage in circular grass buffer integrated cropping systems

Purpose Grass buffer strips enhance ecosystem services of irrigated landscapes. However, their impacts on soil structure and associated soil organic carbon (SOC) and nitrogen (N) cycling have not been documented well for arid and semi-arid agroecosystems. This study aimed to evaluate the seasonal dynamics of dry soil aggregate size distribution, mean weight diameter (MWD), and aggregate-associated SOC and N under buffer strip grasses (BSG), adjacent buffer strip corn (BSC), and continuous conventional corn (CCC) fields without grass buffer in the semi-arid US Southern High Plains. Methods Five circular perennial grass strips alternating with five corn strips in a 3.88-ha quarter-circle area were established under a center pivot irrigation system in the fall of 2016. Soil samples (0–20 cm depth) were collected in the spring, summer, and fall of 2021, 5 years after the long-term grass buffer establishment. Soil aggregate properties were evaluated in grass-corn edge (GCE) and at different distances from the edges in BSC and BSG and various locations in CCC. Results The results show the responses of dry soil aggregate properties varied between treatments and samplings. Specifically, the proportion of macroaggregates (2–8 mm and 0.25–2 mm) varied among treatments in fall and microaggregates (0.053–0.25,