Changing Of Water And Soil Environment Before And After Water-saving Irrigation In Hetao Irrigation And The Simulation Of Water And Fertilizer Efficiency In Farmland

In order to study the influence of water-saving reconstruction in the large scale irrigation district on the regional farmland water and soil environment, this paper selected Jiefangzha Irrigation Scheme of Hetao Irrigation District to be a research area. The influence of reduction irrigation water volume diverted from Yellow River on distribution of soil moisture, nitrate-nitrogen concentration, groundwater quality and drainage water quality were monitored and studied. Furthermore, the typical fields experiment was practiced to analyze crops growth index, soil moisture and nitrate-nitrogen characters under different crops planting structure. At last, the RZWQM model was used to simulate and evaluate maize growth and its irrigation schedule. Then, some results and conclusions were as following:(1) Applied anti-Geostatistics right distance (IDW) interpolation ways to analyse the change of water and nitrogen in time and space and the salinity of groundwater.analyse the Jiefangzha Irrigation District irrigation before and after water-saving renovation project re the quote of the Yellow River Irrigation District irrigation water and nitrogen changes in time and space.It is found that during the implementation of water-saving renovation project ,the leach of nitrate-nitrogen is eased,and the consistency of ground water nitrate-nitrogen is the overall downward trend,the trend pollution of ground water trend was to reduce.the implement of water-saving renovation project have a positive role in improvingnitrate-nitrogen leaching and pollution of ground water,Especially because of reducing autumn storage irrigation, the groundwater level declines, both that lead to obviously reduction of nitrate-nitrogen leaching and pollution, at the same time, the ground water quality was improved. This indicated that the water-saving project and water-saving measures has a significant role to improve the ecological environment for the Hetao Irrigation area.(2) Through the measurement of nitrate-nitrogen for the 22 mornitor points about soil moisture in June and August,the content of nitrate-nitrogen for 0-100cm soil-level have an overall fluctuations in 0-5mg/kg,and the surface soil(0-10cm)have an especially fluctuations. (3) Through the comparison of crop height and leaf area index and different periods of dry matter accumulation for single wheat, corn and wheat single set of corn,we found that single crop's plant height,leaf area index and dry matter accumulation of these three indicators were better than inter-plant crops.The experimental field of soil nitrate content is not particularly high,and the nitrate-nitrogen accumulation is occurred in the 70-100cm layer.There was a high concentrations of soil water solution for nitrate-nitrogen ,and it is much higher than soil nitrate-nitrogen content.In a few days after irrigation the concentration of surface soil water solution increased and then reduced ,the concentration changes significantly,and the 70cm layer has an overall high concentration for nitrate-nitrogen.(4) Through the calibration and simulation for RZWQM model in single corn field of Jiefangzha irrigation in Hetao irrigation,the model can simulate the farmland which is normal irrigation and fertilization.And by the application of the model,come to a more reasonable application of the irrigation system.