Study On Precision Crop Management Model And Decision Support System

The precision crop management model and decision support system is the digital base of making variable prescription, and is the core of precision farming information management. On the basis of the time-course relationships of crop-soil-climate-technology, using the system analysis method and mathematical modeling technique, this study developed a basic framework for design and development of precision crop management model and mainly developed three models including water and nitrogen strategy design model, dynamic of suitable growth indices model and growth dynamics regulation model. By further adopting the component method and integrating the GIS and database technology, a model and GIS-based decision support system for precision farming was established. This work has provided a basic platform for development of precision crop management model, and laid a technical foundation for the practical application of precision farming system.By combining with the experts of crop cultivation and analyzing the crop management problems, a framework and structure of precision crop management model was developed under the guide of system engineering. The model included three modules as pre-sowing plan deign, suitable dynamic indices prediction and real-time regulation according to actual crop growth status. Based on the analysis and extraction of the newest researches on crop cultivation theories and technologies, using the system analysis theory and method, the arithmetic framework of each module was developed by quantifying the time-course relationships of crop growth and cultivation management indices to variety traits, eco-environments and production levels. This work provided the technology guide and framework for effectively using the general function components in the precision crop management model, and for improving the development efficiency of the precision crop management model.Based on the analysis and extraction of the newest researches on crop cultivation theories and technologies, a design model for water and nitrogen strategy in crop was developed driven by quantifying the time-course relationships of water and nitrogen management plan to production levels, variety traits and eco-environments. The model included two modules as nitrogen strategy and water management. The submodel for nitrogen strategy was developed with the principle of nutrient balance and by combining the effects of climate, soil and variety. In the submodel, N demand per 100 kg grain was calculated by classifying the rice and wheat varieties according to yield and quality, and the N demand for grain yield target and indigenous soil N supply were quantified by the grain yield target and the grain yield in the plot without N fertilizer. The submodel for nitrogen strategy can make decisions on the suitable total N rates and the ratio of base to topdressing N. Based on the principle of water balance, the submodel for water management was developed by adopting soil water potential as irrigation index. The model was evaluated using the data from literatures, field experiments of diverse eco-sites and years. The results indicated the model's good guidance and wide applicability.According to the concept of constant physiological development time (PDT), the development stages under different environment were predicted with PDT. Then through dynamically calculating growing degree days required by main development stages under different environments, the dynamic model for growth and nutrient diagnosis and management in crop driven by physiological development time-based relative growing degree-days and relative growth indices was developed.The relative dynamic curve of leaf area index and stem and tiller number was according to the Raditional Function, and the relative dynamic of dry matter accumulation and plant nitrogen accumulation was established according to the growth characteristic of Logitic curve. On the basis of the relative growth indices dynamics, the model for design of growth indices dynamics in crop was developed by calculating the maximal indices under suitable conditions. Case studies with the data from field experiments at Nanjing in three years indicate a good performance of the model system for prediction and wide applicability.Based on the analysis and extraction of the newest researches on crop cultivation theories and technologies, a model for growth dynamics regulation in crop was developed combining with suitable dynamics of indices model, water and nitrogen strategy model. The growth diagnosis indices were confirmed by analyzing the time-course relationships of crop growth dynamics to production levels and eco-environments. The model made the suitable growth and nutrient indices designed by suitable dynamic of indices model as standard expert curve. When the actual crop growth condition departed from the expert curve, the model analyzed the reason and studied out the suitable dressing N application and irrigation amount by calculating the regulation factor and combining with the water and nitrogen strategy model. Case studies with the data sets of field experiments indicated the model's wide applicability and good guidance. The model avoided the deficiencies of regional limitation and empirical decision with traditional crop cultivation patterns and expert systems, and thus provided a promising quantitative tool for crop growth management.On the basis of the precision crop management model, a model and GIS-based decision system for precision farming (MGPFDSS) was established on the platforms of.NET with the programming language of C# by using the techniques of object-oriented and component-based programming and incorporating the GIS. The MGPFDSS provided a modeling, parametric, dynamic and systematic tool for making variable prescription during the process of crops growth and development, and lay a foundation for the development of precision farming and digital farming.