Abstract
Based on our previous work modeling crop growth (CropSPAC) and water and heat transfer in the soil-plant-atmosphere continuum (SPAC), the model was improved by considering the effect of plastic film mulching applied to field-grown maize in North-west China. In CropSPAC, a single layer canopy model and a multi-layer soil model were adopted to simulate the energy partition between the canopy and water and heat transfer in the soil, respectively. The maize growth module included photosynthesis, growth stage calculation, biomass accumulation, and participation. The CropSPAC model coupled the maize growth module and SPAC water and heat transfer module through leaf area index (LAI), plant height and soil moisture condition in the root zone. The LAI and plant height were calculated from the maize growth module and used as input for the SPAC water and heat transfer module, and the SPAC module output for soil water stress conditions used as an input for maize growth module. We used <i>r</i><sub><i>s</i></sub>, the representation of evaporation resistance, instead of the commonly used evaporation resistance <i>r</i><sub><i>s</i>0</sub> to reflect the change of latent heat flux of soil evaporation under film mulching as well as the induced change in energy partition. The model was tested in a maize field at Yingke irrigation area in North-west China. Results showed reasonable agreement between the simulations and measurements of LAI, above-ground biomass and soil water content. Compared with the original model, the modified model was more reliable for maize growth simulation under film mulching and showed better accuracy for the LAI (with the coefficient of determination <i>R</i><sup>2</sup> = 0.92, the root mean square of error RMSE= 1.23, and the Nush-Suttclife efficiency E<sub>ns</sub> = 0.87), the above-ground biomass (with <i>R</i><sup>2</sup> = 0.96, RMSE= 7.17 t·ha<sup>−</sup><sup>1</sup> and E<sub>ns</sub> = 0.95) and the soil water content in 0–1 m soil layer (with <i>R</i><sup>2</sup> = 0.78, RMSE= 49.44 mm and E<sub>ns</sub> = 0.26). Scenarios were considered to simulate the influence of future climate change and film mulching on crop growth, soil water and heat conditions, and crop yield. The simulations indicated that the change of LAI, leaf biomass and yield are negatively correlated with temperature change, but the growing degree-days, evaporation, soil water content and soil temperature are positively correlated with temperature change. With an increase in the ratio of film mulching area, the evaporation will decrease, while the impact of film mulching on crop transpiration is not significant. In general, film mulching is effective in saving water, preserving soil moisture, increasing soil surface temperature, shortening the potential growth period, and increasing the potential yield of maize.
Highlights
Philip[1] proposed the concept of the soil-plant-atmosphere continuum (SPAC), in which the movement of water is a continuous process
Crop growth and soil water transfer interactive processes in the CropSPAC model, which describes the change of canopy temperature and humidity, the process of crop leaf area index (LAI) and height change, soil water and heat transfer and root growth status
Based on this CropSPAC model, here we extended its application to maize and consider the influence of film mulching on the decrease in soil evaporation and the induced change of surface energy partitioning
Summary
Philip[1] proposed the concept of the soil-plant-atmosphere continuum (SPAC), in which the movement of water is a continuous process. A new model (CropSPAC) which couples the simulation of winter wheat growth and water and-heat transfer in the SPAC was recently proposed[27] In this model, the SPAC was divided into three levels, including the soil layer, the crop canopy and the atmosphere at a certain reference height. Crop growth and soil water transfer interactive processes in the CropSPAC model, which describes the change of canopy temperature and humidity, the process of crop leaf area index (LAI) and height change, soil water and heat transfer and root growth status Based on this CropSPAC model, here we extended its application to maize and consider the influence of film mulching on the decrease in soil evaporation and the induced change of surface energy partitioning. The improved model was calibrated and validated on a field site with a maize crop in the middle reaches of the Heihe River Basin of China, and was applied to investigate the influence of climate change and local farming management on crop yield and WUE
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