Research Of Soybean Nutrition Information Diagnosis Based On Spectrum Technology And System Of Variable Rate Fertilizer

Crop Nutrition Diagnosis is a tool for the conduct of investigation and research of crop nutrition and nutrition environment. The main crops biochemical parameters (such as chlorophyll, potassium, leaf area index, nitrogen, etc.) represent the nutritional status of plants, and are closely related to the crop yield. And the plant nutrient content or a likely lack will be reflected on the spectral characteristics. Through an inspection on the optical reflection of the canopy or leaves of plants, we can understand the nutritional status of crops, and achieve that to get the broad area Farmland growing information without damage, fast and accurately. That's significant for understanding and mastering crops growing, nutrition component content, quality and yield information. Precision variable fertilization is an variable prescription Fertilization theory and technology which is based on the multiple analysis on different spatial units of nutrient data, grain output data and other multi-layer composite , as well as the crop growth model, crop nutrition expert system for support , and for the purpose of high-yield, high-quality, environmental protection. Variable rate fertilization technology optimizes and combines 3 S technology (RS, GIS, and GPS), biotechnology, automatic control technology and agricultural engineering equipment technology, and is an important component of the precision agriculture technology.Soybean is an important economic crop in China. Because of a serious shortage of soybean supply, our country became the first major importer from the first soybean production country in the world, thus increasing the soybean yield and quality will become imperative. The variable rate fertilization Based on remote sensing information can supple needed nutrients for growing plants according to the soybean plants growing situation in the real time. This optimized the use of chemical fertilizers, increased soybean production, improve the quality of soybean, and open up a new way for solving the problem of insufficiency of soybean. This paper combined with the state's high-tech plan (863) project "crop nutrition information and morphological parameters Detection Technology" (2003 AA209012) and "variable automatic fertilizer fertilizing machine control and the development of institutions" (2006 AA10A305-7). based on the literature of former information at home and abroad, this research take soybean as the object, base on field trials, integrate apply modern remote sensing information technology, physiological and biochemical tests, mathematical statistical analysis , control technology and other means; build up the spectral information collection support platform supported by the MSR-16 multi-spectral ; build up a spectrum of information processing systems ; derivate variable fertilization decision-making prescription plans according to biochemical content of the soybean forecast model ; develop variable fertilization system software V1.0 with C + + Builder ; use a uniform design software research the relation among duty cycle, the import volume and frequency under certain conditions, optimize the working parameters for the implementation of variable control system , complete field trials of topdressing liquid fertilizing in the soybean podding stage . Elements and conclusions for the research are as follows:1. Explore an predicted model of nitrogen, potassium content based on the sensitive band spectral data for soybean; collect the spectral data for soybean canopy in autumn with MSR16R spectrometer; initially apply anti-Gaussian red edge optical model (IG model) fitting the red edge reflectance rate, derivative the red edge amplitude Dλred after differentiation spectra and establish the nonlinear regression equation to estimate its Nitrogen content:TN = 5.0065-0.5818 * exp [- (194.3980 * X) ~41.3043]2. At the same time extracted absorption depth, one of the spectra characteristic parameters, remove a continuum, and use statistical regression method to estimating the total potassium content, TK = 0.1746 +863.0691 *exp [- (X +0.0741) / 0.1213]Thus achieve forecast nutritional status of the crop only with specific band spectral data, and find out that the red band can be a sensitive band for forecasting soybean nitrogen and potassium content.3. Application of the estimation model for soybean nitrogen, potassium content, establish the variable rate fertilization decision-making geographic information systems based on the spectral characteristics value. Deprive nutrition gradient of six block calibrated experimental area using the diagnosis of nutrition model based on field test data, and establish the parameter prescription plans for later variable rate fertilization according to the traditional fertilization standard, build up the geographic information systems to implement a system of variable rate fertilization.4. Independently develop the software V1.0 to control the variable fertilization system based on C + + Builder 5.5, and complete the controlling of the electromagnetic valve. Use pulse-width modulation technology PWM to control solenoid valve state, opening or closing, realize variable spray of liquid manure using two-way solenoid valve to control spur track.5. Analysis the relation among the electromagnetic valve frequency, duty cycle, nozzle inlet pressure, and different nozzle flow, calibrate the optimum working parameters for field fertilizer. With uniform design analysis software UST4.0, select the experimental plan U12*(127) with four levels for the frequency of X1 and the pressure of X2, and six levels for the duty cycle X3, and establish the regression equation with the former three factors , the hollow cone nozzle flow Y1 and fan nozzle flow Y2.According to the changes in flow, optimized hollow cone nozzle as a working device. According to the analysis, the working fertilizer parameters are deprived from the analysis, the frequency X1 is set to 4 Hz, the pressure on the export X2 is set to 23.2 kPa, and duty cycle X3 is set to 0.4. Thus determine different fertilization duty cycle of the six experimental fields according to the preparatory work for the variable rate fertilization decision-making programmed.6. Developed a variable fertilization experimental prototype, and achieve the overall variable spray. Spray machine developed is composed of spray pump, gasoline engine, solenoid valve, hollow cone nozzle, variable fertilization control systems, and power. Successfully trial-manufacture the variable rate fertilization implemental institutions with a modified agricultural elevated car. Lastly, the field test showed that with a control signal in a certain duty cycle, frequency and locomotive speed, using pulse-width modulation technology can meet the need of field foliar liquid fertilizer with variable fertilization machine, without spray leakage in the advancing direction of locomotive.