Research On Soybean Variable Rate Fertilization Control System Of Precision Agriculture

Precision agriculture is the important modern agricultural production that has developed on the base of the modern information technology, biotechnology, engineering technology and so on.Its core technology is the geographic information systems, global positioning systems, remote sensing technology and computer automatic control technology. Precision agriculture system is a highly integrated complex system and an important way that can make the agriculture low consumption, high efficiency, quality, safety. The implementation of precision agriculture includes many steps, such as agricultural land information collection, information management and decision, variables operation and so on. In particular variable rate fertilizing is an important part to implement precision agriculture among variable operating.Autocontrol variable rate fertiliaztion seeding can make variable rate fertiliaztion digital map-based and put variable data into planter control systems according to the soil properties, grain yield, field land elevation, crop varieties,local climate conditions and so on by agricultural expert system. Heilongjiang reclamation area is a major producing area of soybean, according to its actual situation,if we apply technology of variable rate fertiliaztion to soybean precision planter, it can improve the precision planter and soybean production. On the base of existing level of agricultural resources and production, it can increase the technical level of domestic soybean planting and technological content of soybean production, increase crop yields, reduce the amount of chemical fertilizer, improve fertilizer efficiency, reduce production costs and avoid unnecessary waste, improve overall economic efficiency of agriculture, protect agricultural ecological environment, develop the green organic agriculture and make the sustainable agricultural development,and has broad application prospects and academic value.This article focused on the control technology of precision agriculture soybean variable rate fertilizer according to the "863" project "the construction and application soybean crop precision operating system " and a major project in Heilongjiang Province,"the development of variable solid fertilizer planter basing on GPS autocontrol". After surveyed the situations of precision agriculture variable rate fertiliaztion at home and abroad and refered to relevant documents, it put forward the control system program of large tractor matching soybean planter variable rate fertilizer aiming at large-scale agricultural mechanization in Heilongjiang reclamation area.On the base of analysis on the main influencing fertilizer factors, it ascertained the variable rate fertilization control program that the hydraulic motor serves as implementing agencies. Variable rate fertilization control system consists of DGPS receivers, vehicle-mounted computer, variable rate fertilization closed-loop controller, electro-hydraulic proportional valve, hydraulic motor, fertilizer,etc. Through the hydraulic motor driving the shafts of fertilizer, we can control the speed of planter fertilizer shafts and regulate fertilizer in order to achieve on-demand variable rate fertilization of precision agriculture. When fertilizer apparatus driven by hydraulic motors, without land wheel drive, variable rate fertilization desgin must consider forward speed of the planter impact on fertilizer.According to variable rate fertilization control theory and combining with design requirements, it put forward the program of variable rate fertilization control system concentrating on the board computer and closed-loop controller,and researched the two core parts of control system deeply on this basis.Firstly,the article studied the control tactics of variable fertilization vehicle-mounted computer and the method of GPS information acquisition importantly on the basis of analysis on computer software and hardware composition, and then developed the variable rate fertilization control software and solved the problem of variable rate fertilization operating data storage and analysis on vehicle-mounted computer using Visual Basic 6.0 programming language and Map Objects geographic information control.It also developed the variable rate fertilization closed-loop controller at the core of MCU, and designed a CPU circuit, reset control circuit, signal input circuit, serial communication circuit, LED digital display control circuit, output drive circuit, power supply circuit and so on.It built mathematical model of PID control which has been applyed to the control of hydraulic motor speed closed-loop.It improved the precision of variable rate fertilization.Forward speed of the variable rate fertilizing planter impact on fertilizer has been analysised,and the formula deduced between vehicle-mounted computer fertilizer theoretical amount and motor speed when forward speed of the variable rate fertilizing planter changed.In order to verify the correctness of theoretical analysis and performance of the variable rate fertilization control system, experiment of control system hydraulic bench has been done and data acquisition has been analyed,and the rating experiment and field experiment of soybean variable rate fertilizer planter have been done by installing variable rate control system in the soybean planter. The results of tests showed that the control system of soybean variable rate fertilizer planter had advanced technology, reliable performance, convenient operation and higher precision. It can match with large-scal planter and meet the requirements of precision agriculture variable rate fertilizer control.