Research of the Effects of Different Drip Irrigation Treatments on the Growth of Summer Maize and the Adaptability of AquaCrop Model

Abstract

【Objective】 Bioavailable water in soil controls root growth and root water uptake, but it depends on how water is irrigated. The objective of this paper is to investigate the effect of different drip irrigation methods and amounts on growth of summer maize. 【Method】 A two-year field experiment was conducted in Tianjin, China. It consisted of two irrigation methods: conventional drip irrigation (M1) and mulched drip irrigation (M2), each having two irrigation amounts: 10 mm (N1) and 20 mm (N2). Crop growth in each treatment was measured, and the measured data was used to calibrate the AquaCrop model. The calibrated model was then used to evaluate how the yield responded to irrigation methods and amounts in normal year, from which we obtained the optimal irrigation scheduling to maximize the yield. 【Result】 Soil water content in the top 0~40 cm soil layer under M1+N2 was higher than that under M1+N1 and M2+N2. The biomass and yield under different treatments were ranked in the order of M2+N2 > M2+N1 >M1+N2 >M1+ N1. The R2, EF and RMSE between the simulated and measured soil water contents for all treatments were in the range of 0.645~0.907, 0.461~0.779, and 0.021~0.034, respectively. The R2, EF and RMSE between the simulated and measured canopy coverage were 0.942~0.992, 0.964~0.990, and 0.463~0.781, respectively. The R2, EF and RMSE between the simulated and measured biomass were 0.959~0.984, 0.969~0.986, and 0.507~0.614 t/hm2, respectively. The RMSE between the simulated and measured yield and water use efficiency were 0.180~0.890 t/hm2 and 0.001~0.003 t/(hm2·mm), respectively. 【Conclusion】 Under conventional drip irrigation, increasing irrigation amount can improve water content in the 0~40 cm soil layer; water content in the 0~40 cm soil layer under conventional irrigation was higher than the mulched treatment when irrigation amount was 20 mm. Mulching or increasing irrigation amount can improve biomass and yield of the summer maize. The AquaCrop model can reproduce the growth of summer maize. The optimal irrigation scheduling to maximize maize yield in the studied region is to irrigate 20 mm of water at seedling stage, 10 mm at heading stage, and 10 mm at filling stage.

Keywords

• aquacrop model
• summer maize
• soil water content
• canopy coverage
• biomass and yield
• wue