Optimizing maize productivity: A sustainable approach integrating straw derivatives and film mulching in rainfed agriculture

Context or problem: Resource-use inefficiency, environmental degradation and food security are forcing a transformation from conventional to organic and sustainable agriculture. Objective or research question: Realizing synergistic use of light, water, and nitrogen resources for spring maize in a more circular straw utilization model, while comprehensively evaluating the sustainability of the scheme is the key to solving the above problems in rainfed areas, but there are few reports. Methods: According to a crop-livestock-biogas digester straw recycling model, straw can be returned to the field directly or in the form of cattle manure after fattening, or cattle manure can continue to be recycled by the digester as the only fermentation substrate, and ultimately returned to the field indirectly in the form of biogas residue. Therefore, according to different levels of straw recycling, four treatments were set up in this study: straw (S), cattle manure (M), biogas residue (BR) and control (CK) for a comparative study of water use efficiency, net solar radiation use efficiency, photosynthetic and leaf characteristics post-anthesis, annual nitrogen balance, spring maize yield, and sustainability index. Results: The results showed that straw and its derivatives effectively improve the utilization efficiency of light and water, potentially reducing the adverse effects of factors on yield variability. Maintaining high levels of photosynthetic activity after anthesis was mainly due to the positive effects of organic amendments on nitrogen content per unit leaf area. This led to significant increases in grain yield and harvested index by 5.95% to 13.22% and 3.41% to 6.37%, respectively. However, exogenous organic N addition promoted N2O emission and NH3 volatilization, resulting in a higher N surplus. The sustainable index of each treatment was in the following order: BR>M>CK>S. Conclusions: Long-term organic amendments, especially BR, can effectively improve the utilization and synergistic effects of critical production resources, constituting a high-yielding, efficient and sustainable spring maize population, which is consistent with our hypothesis that the sustainability index is higher in more circular straw utilization. Implications or significance: This study provides a new plastic film cultivation strategy and evaluation perspective for sustainable spring maize production in the study area or similar areas.