Soil Fertility Evaluation And Fertilization Decision Support System On Shanghai Farm

For5000hm2cultivated lands of Shanghai Farm, GPS technology was employed to take429soil samples to test fertility index such as soil salt content, pH, soil organic material, total nitrogen, available nitrogen, available phosphorus, available potassium etc.. This research also analyzed the grade distribution of soil fertility factors, statistical characteristics and spatial distribution characteristic of the soil samples. Based on four representative field experiments, absorption parameters of nitrogen, phosphorus and potassium in wheat and rice under high-yielding conditions was obtained, and then the fertilization decision-making models was established upon piggery wastewater and fertilizer formula application. Finally the research constructed a crop fertilization decision support system of Shanghai Farm. The main results are briefly summarized as follows:1. Evaluation and distribution characteristics of soil fertility on Shanghai Farm.The mean value of soil salinity was about0.13%, concentrating around from0.1%to0.2%, taking proportion of78.09%. The organic matter contents were in the range of10to30g/kg account for99.07%of the soil samples, averaging19.56g/kg.The mean value of total nitrogen was about1.10g/kg, concentrating around from0.75to1.5g/kg, taking proportion of89.75%.The mean value of alkali-hydrolysable N was about72.62mg/kg, concentrating around from60-90mg/kg, taking proportion of72.49%.The mean value of available phosphorus was about23.02mg/kg, concentrating around from10to40mg/kg, taking proportion of93.47%.The mean value of available potassium about189.70mg/kg, concentrating more than150mg/kg, taking proportion of76.93%. The comprehensive evaluation values of all production teams’soil fertility were from0.45to0.55, showing that the soil integrative fertility was at intermediate level.The content of pH, salty, available phosphorus and available nitrogen on the farm increased with longitude, however the content of organic matter decreased with longitude. The variety of soil total nitrogen, available nitrogen contents were not obvious as the change of longitude. The content of soil pH, salinity, total nitrogen and available nitrogen showed no trend with the latitude. Organic matter and available phosphorus contents decreased with latitude. On contrast, available nitrogen content had no relation with latitude. The distance to the coastline has similar influence as latitude on the value of soil fertility indexes due to the narrow latitudes range distribution of the samples, while the coastline in Dafeng is in west of about20°.2. Wheat and rice nutrients parameterBase on two experiments of wheat under application of NPK fertilizers and piggery wastewater with chemical fertilizer, N absorptive amount per100kg grains for high-yielding wheat (with straw) was2.438kg and2.010kg respectively, P absorptive amount (without straw)0.372kg and0.362kg respectively and K absorption amount (without straw)0.195kg and0.311kg respectively. Based on two experiments of effects of applying phosphate to machine-transplanted rice and combined piggery wastewater with chemical fertilizer, the amount of nitrogen absorption of100kg grains for high-yielding rice(with straw) was1.612kg and1.810kg respectively, P absorptive amount (without straw)0.240kg and0.241kg respectively and K absorptive amount (without straw)0.229kg and0.232kg respectively.3. Fertilization decision support systemBased on component type GIS technology, this research developed a decision support system for fertilization with good features of friendly interface, comprehensive functions, and rich contents. The system included functions of soil fertility query and searching, data management, thematic map making, fertilization decision, learning guidance and so on.