Modeling effects of biodegradable film mulching on evapotranspiration and crop yields in Inner Mongolia

The use of biodegradable film has been increasingly recommended as an alternative to conventional plastic films. Several studies have evaluated the applicability of biodegradable film mulching (BRM). However, the large-scale effects of BRM on the spatiotemporal distribution of evapotranspiration (ET) and crop yields remain unclear. Furthermore, existing DSSAT (decision support system for agrotechnology transfer) models cannot accurately represent crop yields, as they fail to account for the impact of the disintegration rates of biodegradable films (DR) on air temperature (Ta) compensation, which represents the effect of soil temperature changes in mulched conditions on crop growth in the form of air temperature changes. Therefore, this study proposed an improved DSSAT model under BRM (BDSSAT) by considering the impact of DR on Ta compensation, and the performance of the model was compared with those of the DSSAT and modified DSSAT (MDSSAT). These models were validated using observed data from nine typical experimental sites in Inner Mongolia from 2015 to 2018. Moreover, 96 meteorological stations and soil textures were selected to evaluate the effect of BRM on soil water storage (SWS) (the amount of water stored in a given soil body, mm), ET, and crop yields of the primary cultivated crops (sunfiower, potato, corn). Our findings demonstrated that the BDSSAT model could accurately simulate the SWS, ET, and crop yield under BRM. The normalized root mean square error (nRMSE) of ET simulated by the BDSSAT model was 49.4 % and 66.3 % lower than that of the MDSSAT and DSSAT models, respectively. An apparent spatial difference in SWS, ET, and crop yield was found in different regions due to the differences in soil texture, meteorological data, and agricultural management strategy. The spatial distributions of ET and crop yield of sunfiower, potato, and corn in different regions were largely consistent with the spatial distribution of SWS. Furthermore, the ET and crop yield of sunfiower and potato crops in different regions increased with time (2015-2018) due to an increase in rainfall. However, these effects were not observed in corn yields in the eastern region. Additionally, the DR in the western, middle, and eastern regions should not exceed 55 %, 73 %, and 90 %, respectively, to ensure high field production (crop yield was higher than the historic average). Crop yields in different regions increased in response to future climate change, as the average Ta was projected to increase by 0.8 degrees C from 2019 to 2050, except for sunfiower yields in the western region.