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Plastic film mulching (PM) has been extensively used to increase crop yields in dryland regions in China. However, the impact of differently colored PM on crop radiation utilization due to the optical properties of the underlying PM surfaces remains unclear. We conducted a two-year field experiment in northwest China to evaluate the dynamics of photosynthetically active radiation interception and absorption (fIPAR and fAPAR), as well as the radiation use efficiency for intercepted and absorbed radiation (RUE i and RUE a) during spring maize (Zea mays L.) growth periods. Two fertilization levels (high and low) and 3 PM treatments (transparent film, black film, and no film) were considered in this study. We also developed empirical regression functions to calculate canopy fAPAR, accounting for both canopy and underlying surface characteristics. Furthermore, we used canopy absorption radiation to drive the Soil-Plant-Atmosphere Continuum System (SPACSYS) model to simulate maize biomass and yield. We found that transparent film mulching (TM) exhibited higher fIPAR and fAPAR than black film mulching and no mulching (CK). TM had an increase of RUE i and RUE a by 10.6% and 9.7%, respectively, relative to CK, resulting in a 9.3–19.2% increase in maize yield and a 25.8–30.2% increase in the partial factor productivity of nitrogen. These increases were mainly attributed to the increased relative chlorophyll content, net photosynthesis rate, and extended grain-filling period under TM. We found that the modified radiation input increased the accuracy of the SPACSYS model in simulating maize biomass and yield. We underscore the importance of using TM in dryland areas to increase crop yields and advocate for incorporating canopy radiation data into crop models, especially in agricultural regions where plastic film mulching is used, to enhance the accuracy of yield simulations. • Transparent film mulching (TM) with high nitrogen produced the highest maize yield. • TM increased light intercept and absorbed fraction (fAPAR). • We established empirical regression functions to calculate canopy fAPAR. • Soil–Plant–Atmosphere Continuum System (SPACSYS) model well simulated yield with modified radiation input data. [ABSTRACT FROM AUTHOR]

The widespread adoption of returning crop residue to regulate soil properties and improve yields has been well-established. However, the long-term effects of residue return on soil organic carbon (SOC) and yield in film-mulched farmland, especially under future climate conditions, are still unclear. To address this issue, we utilized the SPACSYS model, which was calibrated with 5-year (2016–2020) field experiment data from various mulching and fertilization treatments in the Hetao irrigation district in northwest China. Furthermore, we investigated the impacts of climate change on SOC storage in 20 cm and maize yield with calibrated SPACSYS model driven by 27 global climate models under two climate scenarios (SSP245 and SSP585) from CMIP6. We considered multiple combinations of agronomic options: five residue return levels (R1: 20%; R2: 40%; R3: 60%; R4: 80%; R5: 100%) and three return depths (D1: surface applied; D2: 10 cm; D3: 20 cm) to evaluate the effects of residue return on SOC storage and yield. We found that yield at a high fertilization rate with transparent film mulching (HT) would increase by 10.1% under SSP245, 15.3% under SSP585 in 2021–2060 compared to the baseline (1981–2020). By contrast, the yield would decrease by 5.8% under SSP245, 21.7% under SSP585 in 2061–2100. SOC storage under HT would decrease by 9.4–12.7% and 18.4–41.4% in 2021–2060 and 2061–2100, respectively. We determined that the optimal treatment involves returning 100% of residue to a depth of 20 cm (R5D3). Under R5D3, yield showed an increasing trend in both two future periods; the SOC storage decreased by 4.8–6.8% in 2021–2060 and increased by 3.9–16.1% in 2061–2100 compared to the baseline under HT. Our results highlight the potential of residue return to increase yield while maintaining soil health when film mulching is adopted. • SPACSYS model simulated yield and soil organic carbon (SOC) content well. • SOC stocks show a declining trend in the future without residue return. • Residue return can mitigate negative effects of climate change on yield and SOC. • The optimal choice for augmenting SOC and yield is 100% residue return at 20 cm. [ABSTRACT FROM AUTHOR]