Simulation Analysis of Moisture Movement in Wheat Field Micro-sprinkler Irrigation

According to characteristics of moisture distribution of micro sprinkler irrigation in the middle and late stage of winter wheat，soil moisture movement and distribution in the root zone of wheat in the middle and later stages of wheat were discussed under different irrigation factors.Irrigation intensity under different irrigation pressure was measured by experiment.Effective humid region was divided into four sub-regions，and different irrigation intensity was obtained as irrigation boundary condition.Considering water absorption of winter wheat roots，equations of micro-sprinkler irrigation soil water movement and solving conditions were established.By comparing and analyzing simulation results and experimental data of micro-spray irrigation，HYDRUS-2D numerical simulation was proved to be effective in soil moisture distribution.On the basis of this model，influence factors of different irrigation pressure，different irrigation lower limit and different laying distance of micro-spray belt were simulated and analyzed.Results showed that effective wet area was large and water distribution could meet demand of wheat root system without water waste under irrigation pressure of 0.15 MPa；taking 60% of field water capacity as lower limit of irrigation was beneficial to reduce laying cost of micro spray belt，save irrigation water and increase utilization rate of irrigation；at interval of 440 cm，soil moisture distribution in the root was a uniform band，and uniformity was about 90%，which could make each wheat get the same irrigation water quantity.Above results could not only provide reasonable operation parameters for laying and running of micro-spray belt，but also provide theoretical reference for water-saving irrigation of wheat.