Soil drying shapes rhizosheath properties and their link with maize yields across different soils

Background and Aims: Biophysicochemical soil properties in the rhizosheath are pivotal for crop yields and drive organic carbon cycling in agricultural soils. Yet, it remains uncertain how moderate soil drought may alter and interfere with rhizosheath properties in diverse soil types, and whether specific rhizosheath traits benefit crop yields under different water availability in heterogeneous field environments. Methods: Maize (Zea mays L.) was grown under ambient precipitation and moderate drought (60% precipitation exclusion) at two field sites differing in physicochemical soil properties, such as texture and amounts of soil organic matter (SOM). Rhizosheath properties, namely soil aggregation as well as content and distribution of carbon (C) and nitrogen (N), were analyzed and, in conjunction with root traits, related to maize yields. Results: Under moderate soil drought, net rhizosheath-C concentrated spatially within the smaller rhizosheath in the form of more carbon-rich rhizodeposits. These effects were mediated by native soil properties, with rhizosheath structural stability decreasing stronger under drought in the finer-textured soil, allocating greater proportions of C and N to microaggregates. Rhizosheath and root properties were associated with maize yields. Yet, the influence and importance of belowground traits for crop yields varied with environmental conditions (soil x precipitation). Conclusion: The responsiveness of rhizosheath properties to moderate soil drought may influence the fate and turnover of root-derived C, and thus the overall drought resilience of SOM in agricultural soils. Moreover, our findings underscore the importance of rhizosheath properties for crop yields, yet highlighting that these relationships differ among environmental scenarios.