Effects of straw application on soil hydrothermal conditions and crop yield in a maize and wheat rotation system

The addition of crop straw is considered an important measure for sustainable agricultural production. Crop straw when incorporated into the soil affects crop growth and development by changing the hydrothermal conditions of the soil. However, quantitative studies that inform on the mechanisms by which added straw or straw biochar (SSB) affects hydrothermal response of soil and thereby crop productivity in lime concretion black soil (LCBS) are lacking. Moreover, the sustained effects during continuous cropping are less well understood. The impact of SSB on soil properties and crop yields in a typical LCBS area was systematically investigated through field experiments with maize and wheat rotations. Four treatments were set: straw (S), fertilizer (F), straw with fertilizer (SF) and straw biochar with fertilizer (BF). The results indicated that soil water-holding capacity and rainfall storage efficiency were improved in BF and SF treatments. Compared with the F treatment, the soil water storage increased by 80%–98% and the response time of soil water to rainfall was advanced by approximately 4 h in the other three treatments during the maize season. BF and SF treatments only increased soil water storage by 6.8% due to the lack of rainfall during the wheat season. Soil inorganic nitrogen and available phosphorus were significantly increased in SF treatment by 101.1% and 32.9% compared with BF treatment in the wheat season. Considering crop plant height, leaf area index and yield, SF and BF treatments were beneficial to crop growth and improved water use efficiency. They did not increase maize yield significantly, with a maximum increase of 2.1% in BF treatment compared with F treatment. But, SF treatment significantly increased wheat yield by 11.8% and BF treatment increased wheat yield by 6.7%. Overall, this study illustrated the positive effects of SSB additions on the production of LCBS from multiple perspectives. This will provide reference for improving the soil hydrothermal conditions of LCBS and ensure food security.