Effects of ridging and plastic film mulching on the water balance of summer maize during its growth period

Under the background that the water-saving irrigation theory is widely promoted and applied, ridging and mulching as a common planting method are widely used in various regions. However, whether the water-saving effect of ridging and mulching is suitable for corn production in the semi-arid region of the northwest of Liaoning is still controversial. In this paper, a field experiment was carried out at the water-saving irrigation experimental station in Jianping County. Four types of underlying surface treatments were set up, including flat planting without plastic film mulching (NL-NM), ridge planting without plastic film mulching (L-NM), flat planting with plastic film mulching (NL-M), and ridge planting with plastic film mulching (L-M). The three typical years of wet (2001), general (2014), and dry (2008) were selected from 2000 to 2022, and the change law of water balance during the growth period of summer maize in different typical years was explored by combining with the Hydrus-2D model, The effects of ridging and mulching on rainfall infiltration of underlying surface and water balance of farmland during growth period were analyzed. The results showed that the R² of the simulated values and the measured values of the four underlying surface treatments of the field test by the Hydrus-2D model were above 0.87, and the RMSE was within 0.01. It can be seen that the simulation effect of the Hydrus-2D software on the dynamic change process of soil moisture content after rainfall in various tillage methods was good, and it can be used to explore the change law of water balance in the growth period of summer corn in different typical years; Ridge and film mulching can increase the water content in the soil and the vertical infiltration rate after rainfall, and will not cause the uneven distribution of water in the soil after infiltration stabilization due to the impermeability of the film and the change of the shape of the underlying surface; Plastic film mulching can significantly increase the transpiration rate and reduce the evaporation rate of crops during the growth period. After plastic film mulching, the cumulative evaporation in each typical year decreases by 52.24 mm on average, and the cumulative transpiration increases by 31.84 mm on average; The film mulching will inhibit the deep leakage rate during the continuous rainfall for many days, and promote the deep leakage rate after the rainfall of more than 40 mm in a single day; Film mulching can reduce the evaporation and deep leakage during the growth period of crops, increase the transpiration, and then reduce the water consumption of farmland during the growth period of crops, so that the average water consumption of farmland in each typical year can be reduced by 25.74 mm. At the same time, ridging treatment can further reduce the water consumption of farmland by 8.16 mm; In each typical year, with the increase of the width of film mulching on the underlying surface of ridging and film mulching, the cumulative reduced evaporation during the crop growth period is greater than the increased transpiration and water consumption, and the water consumption of farmland is gradually reduced, with a total decrease of 13.11 mm in the dry year, 18.47 mm in the normal year, and 23.17 mm in the wet year, except that the water storage of farmland with a film width of 50 cm in the normal year and the dry year is negative, Other simulation schemes of L-M underlying surface have positive farmland water storage, which will not cause soil water loss during crop growth.