Organic amendments improve wheat root growth and yield through regulating soil properties

Organic amendments prevent soil degradation and sustain crop production, but their effects on root growth and its functional responses to variations in soil properties have not been fully understood. A two-year field experiment was conducted to investigate the impacts of organic amendments on soil properties, root growth, and grain yield of winter wheat (Triticum durum Desf.) in the Guanzhong Plain (GZP), China. The five treatments were: application of mineral fertilizer alone (control, CO) and along with 20 Mg ha⁻¹ of wheat straw (MWS), wheat husk (MWH), farmyard soil (MFS), and bioorganic fertilizer (MBF). Organic amendments increased soil organic matter (SOM, 7–15%) and total soil nitrogen (TSN, 5–15%) in the 0- to 40-cm depth compared to the CO treatment. Meanwhile, organic amendments improved soil structure by increasing water stable aggregates (WSA, 5–16%) and macroporosity (ε10, 27–47%). Compared to the CO treatment, organic amendments significantly increased the root length density (RLD) and root mass density (RMD) in the 20-cm depth of soil at the flowering stage. The significantly higher RLD and RMD were also exhibited in the MWH and MFS treatments in the 20- to 100-cm depth. Additionally, the responses of RLD and RMD to WSA and ε10 were well-described by quadratic equations based on all treatments. Importantly, the MWS treatment had the greatest grain yield among all five treatments with better soil fertility and structure. We suggested that the MWS treatment is an effective method for improving soil properties and crop productivity in the GZP