Development of RZ-SHAW for simulating plastic mulch effects on soil water, soil temperature, and surface energy balance in a maize field

Authors: CHU, XIAOSHENG - Northwest Agricultural University; Flerchinger, Gerald; Ma, Liwang; FANG, QUANXIAO - Qingdao Agricultural University; Malone, Robert - Rob; YU, QIANG - Northwest Agricultural University; HE, JIANQIANG - Northwest Agricultural University; WANG, NAIJIANG - Northwest Agricultural University; FENG, HAO - Northwest Agricultural University; ZOU, YUFENG - Northwest A&f University

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2022
Publication Date: 4/28/2022
Citation: Chu, X., Flerchinger, G.N., Ma, L., Fang, Q., Malone, R.W., Yu, Q., He, J., Wang, N., Feng, H., Zou, Y. 2022. Development of RZ-SHAW for simulating plastic mulch effects on soil water, soil temperature, and surface energy balance in a maize field. Agricultural Water Management. 269. Article 107666. https://doi.org//10.1016/j.agwat.2022.107666.
DOI: https://doi.org/10.1016/j.agwat.2022.107666

Interpretive Summary: Plastic mulching is a widely used practice in China to save water and improve soil temperature. Mechanistic approaches to simulate the effects of plastic mulch on the soil water balance and soil temperature dynamics have rarely been studied, however. Our objectives were to modify RZ-SHAW (a version of the Root Zone Water Quality Model that incorporates the Simultaneous Heat and Water Model) to include a plastic film mulch module to simulate the soil surface water and energy balances. The modified model was evaluated with three years of maize (Zea mays L.) data in China. Results suggest that the modified RZ-SHAW model can adequately simulate the dynamics of soil water and the evapotranspiration under plastic mulch. The soil temperature under mulch was better simulated during early growth stages, but slightly overestimated during middle and later stages. However, simulated maize growth and yield were not different between mulched and non-mulched treatments due primarily to the lack of water stress simulated during the study period. Overall, the revised RZ-SHAW model adequately simulated soil water and heat exchange under plastic mulch conditions, but still needs to be improved with regards to crop growth and yield.

Technical Abstract: Mechanistic approaches have been developed to simulate the effects of plastic mulch on the soil water balance and soil temperature dynamics. However, these have rarely been implemented into comprehensive agricultural systems models. Our objectives were to modify RZ-SHAW (a version of the Root Zone Water Quality Model that incorporates the Simultaneous Heat and Water Model) to include a plastic film mulch module that simulates the soil surface water and energy balance, and to evaluate the model's performance over three years of maize (Zea mays L.) production in China. Results suggest that the modified RZ-SHAW model can adequately simulate soil water under plastic mulch, with a mean Root Mean Square Error (RMSE) of 0.024 cm3 cm-3 in all soil layers. Moreover, the revised model can simulate the evaporation reduction and transpiration increase caused by plastic mulch. The soil temperature under mulch was better simulated during early growth stages, but the model slightly overestimated values during middle and later stages. The simulated soil temperature increases caused by plastic mulch were about 1.0' greater than the measured data. Simulated maize growth and yield did not respond to observed differences between mulched and non-mulched treatments primarily because water stress was not evident during the study period. The model does not directly simulate potential effects of plastic mulching on photosynthetic rates, root development, and phenology. Overall, the revised RZ-SHAW model adequately simulated soil water and heat exchange under plastic mulch conditions, but still needs to be improved with regards to crop growth and yield.