Assessment and modeling of maize evapotranspiration and yield with plastic and biodegradable film mulch

Biodegradable film mulching (BFM) in various crops is a good alternative to plastic film mulching (PFM). However, the difference in field water consumption between BFM and PFM has not been fully investigated. A four-year experiment with an improved evapotranspiration (ET) model (BSW) was performed to systematically evaluate and compare the effects of BFM, PFM, and no film mulching (NFM) on ET dynamics. The experiments were done in the Hetao Irrigation District of China at the Baleng experimental station (B station) with sandy soil in 2016-2017 and the Jiuzhuang experimental station (J station) with sandy loam soil in 2018-2019. The results of multi-year verification illustrated that the model accuracy was well-supported during 2016-2019 with mean absolute error (MAE) of 9.0%-16.9% and 13.1%-19.1% for ET and evaporation (E), respectively. The average cumulative ET (CET) under FM (i.e., BFM and PFM) was 443.5 mm each year and decreased by 13.4% compared to NFM. However, there was an obvious difference in CET during the different hydrological years, especially in the early crop growth stages. In the wet years (2016 and 2018), the average CET under FM increased by 6.2%-7.0% compared to NFM but decreased by 7.1%-11.8% in the dry years (2017 and 2019). The transpiration (T) difference between FM and NFM primarily appeared in the early crop growth stages, and T/ET under FM was significantly higher than with NFM by 46.9%-50.2%. An obvious E difference between BFM and PFM was observed in the later crop growing stages due to a greater area of the disintegrated biodegradable film. Additionally, crop yield under PFM and BFM increased by 35.4% and 28.3% compared with NFM, respectively, and water use efficiency (WUE) increased by 47.1% and 35.8%, respectively. Thus, biodegradable film is recommended to replace plastic film to effectively promote the development of sustainable agriculture.