Development Of Crop Nitrogen Non-Destructive Monitoting Instrument Based On Canopy Spectral Reflectance

Precision agriculture which bases on collection technology of information, decision support technology and intelligent equipment to carry out quantitative decision and variable investment for agricultural production with executing in accurate position is the production management technical system of modern agriculture. Accurate agriculture is very important for high limit excavating production potential of land, improving the agricultural efficient use and protecting ecological environment of farmland, and it have embodied fully according to local conditions and scientific management idea. It will be developed direction of modern agriculture. Furthermore, farmland collection technology of information and equipment are basic and sustain of accurate agriculture and important guarantee of realization high efficiency, high yield and high quality agriculture.Nitrogen is the most important element in 6 big elements for crop growth, and is indispensable element of the chloroplast and protein in crop body. Lack of nitrogen can influence quality, yield and the growth development of crop. Therefore, it is important for guidance production of crop and accurate fertilization that nitrogen condition of crop is real time and conveniently got.The multi-channel non-destructive diagnosing instrument for crop growth based on reflection spectrum of canopy was developed in the base of domestic and international research accomplishment on spectrum inspection technology and spectrum model. The paper has introduced principle, design of photoelectric sensor and the software and hardware of the instrument in detail. The instrument adopted C8051F005 as microprocessor with light circuit of collection and conversion, converting circuit of multi-channel signal and digital-to-analogue, keyboard and LCD display circuit and saving data circuit. Software of suspending and awakening has been designed by the low power consumption characteristic of the chip, which can save a lot of electrical energy. The instrument can calculate such agronomy parameter as nitrogen content of rice and wheat, the accumulated nitrogen of rice and wheat and leaf area index (LAI) by detecting light incident and reflection light of 4 specific wavelength to get relevant reflection ratio of canopy and combing related agronomy mathematical model. The inspection instrument is such character as portable, small volume, light weight, strong real time and high speed getting farmland information. The precision of the instrument is very high and the practicality is good through test in the field.