Polyethylene film mulch (PM) is a kind of widely used technology to improve crop yields worldwide; however, because of a problem related with plastic residual pollution, it has gradually been replaced by biodegradable plastic film mulch (BDP). Although BDP has helped to solve the plastic residual pollution, its consequences in terms of greenhouse gas (GHG) emissions have rarely been revealed. Related knowledge is important for forming low-carbon development strategies for the plastic industry and agriculture. The objective of this study is to evaluate the influence of BDP on GHG emissions at different stages of its life cycle, and determine whether replacing polyethylene (PE) film with BDP film is a helpful way to reduce national GHG emissions. The results of this study suggest that the application of BDP improved the GHG emissions associated with agricultural inputs, but induced lower GHG emissions at the growing stage and the waste disposal stage, and resulted in lower total area-scale GHG emissions. Compared to the no mulch (NM) cultivation system, the yield-scale carbon footprint was reduced in both the PM and BDP cultivation systems, which meant that both PM and BDP produced lower GHG emissions than NM for the production of the same amount of grain. It was concluded that BDP is not only a measure to control the problem of plastic residue pollution in agriculture, but it can also mitigate the GHG emissions.

Returning straw to the field is a crucial practice for enhancing soil quality and increasing efficient use of secondary crop products. However, maize straw has a higher carbon-to-nitrogen ratio compared to other crops. This can result in crop nitrogen loss when the straw is returned to the field. Therefore, it is crucial to explore how different methods of straw return affect maize (Zea mays L.) farmland. In this study, a field experiment was performed with three treatments (I, no straw returned, CK; II, direct straw return, SR; and III, straw returned in deep furrows, ISR) to explore the effects of the different straw return modes on soil carbon and nitrogen content and greenhouse gas emissions. The results indicated that the SR and ISR treatments increased the dissolved organic carbon (DOC) content in the topsoil (0–15 cm). Additionally, the ISR treatment boosted the contents of total nitrogen (TN), nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), dissolved organic nitrogen (DON), and DOC in the subsurface soil (15–30 cm) compared with CK. When it comes to greenhouse gas emissions, the ISR treatment led to an increase in CO₂ emissions. However, SR and ISR reduced N₂O emissions, with ISR showing a more pronounced reduction. The ISR treatment significantly increased leaf and grain biomass compared to CK and SR. The correlation analyses showed that the yield was positively correlated with soil DOC, and soil greenhouse gas emission was correlated with soil NO₃⁻-N. The ISR technology has great potential in sequestering soil organic matter, improving soil fertility, and realizing sustainable agricultural development.

Biogas slurry topdressing (BSTD) is a promising strategy for efficient liquid waste utilization and sustainable agricultural production. However, the field-scale regulation of soil dissolved organic carbon (DOC) by BSTD remains insufficiently understood across crop growth stages and soil depths. Therefore, this field experiment investigated the temporal and spatial responses of soil DOC to BSTD during the middle and late stages of maize growth. The results showed that, compared with pure chemical fertilizer topdressing (CF), BSTD increased soil DOC content at the tasseling stage (VT) but decreased it at the milk stage (R3), while the ultraviolet–visible spectrum slope ratio increased at both stages and decreased at the maturity stage (R6). The fluorescence index (FI), freshness index (β:α), and biological index (BIX) increased with soil depth but decreased with maize growth stage. Overall, BSTD promoted increases in FI (2.08%), β:α (3.80%), humification index (2.83%), and BIX (3.98%), and altered soil DOC composition by increasing the proportions of humic acid-like substances (5.86%) and soluble microbial by-products (4.97%). Additionally, partial least squares path modeling indicated that soil depth was the most direct and significant factor regulating excitation-emission matrix indices, organic components, and soil DOC content. By linking BSTD-derived inputs with crop-stage dynamics and soil-profile heterogeneity, this study clarifies how biogas slurry reshapes DOC transformation and partial stabilization under field conditions, providing a scientific basis for the sustainable agricultural use of biogas slurry in dryland agriculture. Graphical Abstract