Monitoring and regulation management system of water, nutrient and salinity in farmland based on WebGIS

Monitoring the dynamic changes information of water, nutrient and salinity, analyzing and diagnosing, and putting forward regulation and control plan, are the basement of improving the production management level of saline alkali farmland. This paper developed a monitoring and regulation management system of water-nutrient-salt in saline alkali farmland based on WebGIS platform, Silverlight 5 and WCF (windows communication foundation) technology. And the technologies of point data monitoring, spatial analysis, and visualization were fused in the system. A series of models that included 15 models (3 kinds) for characteristics analysis, diagnosis and early warning, and control decision of farmland soil water, fertilizer, saline and alkali were set up. And the models were constructed based on the principle of statistics, the principle of water, fertilizer, salt and alkali balance of crop, and the stress response principle of crop to soil water, nutrient, salt and alkali. The system and the models were integrated and applied. The results showed that a whole process optimization management system of "integration of six aspects" was formed, providing an effective assistant decision-making tool for the production management of saline alkali farmland. The system integrated data collection, data management, statistical analysis, diagnosis and early warning, control and decision-making technology and implementation management measures. The results of data processing and analysis of the models were proved to be scientific and effective, and the system application decision was proved to be realistic. The system was applied in Wudi County, Shandong Province, China. The application results showed that the management plan proposed by the system effectively alleviated the salt and water restriction, and the desalination rate of soil salt reached 12.86% in 3 years. The scheme promoted the role of nutrient regulation and fertilizer reduction decision-making measures, and soil nutrient tended to be stable and balanced in space in general. The input-output benefits and production decision efficiency of agricultural production had been significantly improved. The comprehensive water saving rate in the years of 2014-2016 was up to 31.02%, and the nutrient saving rates of N (nitrogen), P (phosphorus) and K (potassium) were 28.69%-63.14%, 10.07%-67.98%, and 97.98%-100% respectively. Wheat and corn yield increased respectively by 10.60% and 16.36% annually, which were close to the expected. The study also found that soil salinity and pH value showed a phenomenon of "salt lowering and alkali rising". Soil moisture had a negative correlation with pH value, but it was not a simple functional relationship. The organic matter increased under the effect of applying organic manure, especially the double-season crop straw returning to field, but its later growth rate was slowed down rapidly, which was related to the raising of corn silage and the decrease of organic matter returning to field. The effective nutrient was affected by the amount of fertilizer, the way of fertilization and the absorption and loss of crops, and the fluctuation was large. So regulatory intention in short term was difficult to be realized. All these phenomena need to be further studied and discussed. In addition, due to the low reliability of the Yellow River's water sources, the role of the system was limited. It is suggested that reservoirs or river interception should be used to store water. The research is helpful to explore the dynamic rule of water, nutrient and salinity in saline alkali soil by means of information technology and improve the precision management in the field.