Characteristic Wavelength Selection And Quantitative Analysis Of Nutrients In Compound Fertilizer Using Near-infrared Spectroscopy

According to the statistics data, the fertilizer production was66,198,000tons accounting for a quarterof the world and the annual consumption was55,617,000tons accounting for one third of the world, in2010. The compound fertilizer is a big part of fertilizers. It is necessary to strengthen the determination andsupervision for quality of compound fertilizer because there are many problems existing in the production,quality and determination of compound fertilizers. In generally, the traditional chemical method is used todetermine the nutrients of compound fertilizer in laboratory, but it also has some defects, such ascomplicated for operation, waste of time and energy, security risk and pollution of environment.The NIRhas many advantages, such as simple for operation, undamaged and instant determination. There weremany studies of organic manure using NIR, but very few of compound fertilizers. In order to determine thecontents of nutrients using NIR, we researched the selection of characteristic wavelength of TN and P2O5incompound fertilizers by NIR and traditional methods. The main conclusions are as follows:�'�The correlation coefficients are over than0.97by using NIR PLS to determine the TN incompound fertilizers of urea and ammonium nitrates as raw materials. The TN content accuracy of urea islower than ammonium nitrate, but the stability is higher, and the qualified rate is also2.2%higher.�'�The correlation coefficients are over than0.94by using NIR PLS to determine the P2O5incompound fertilizers of ammonium dihydrogen phosphate and calcium hydrogenphosphate as rawmaterials. The P2O5content accuracy of ammonium dihydrogen phosphate is higher than calciumhydrogenphosphate, and the qualified rate is also3.7%higher.�'�The correlation coefficients are over than0.87by using PCR to determine K2O in compoundfertilizer of potassium chloride and potassium sulphate as raw materials, and the accuracy of potassiumchloride compound fertilizer is higher than potassium sulphate compound fertilizer.�'�Interval PLS is a good method to select characteristic wavelength of TN in compound fertilizer ofurea and ammonium nitrate as raw materials. The TN characteristic wavelength is1297.8～1497.8nm inurea compound fertilizer, and the characteristic absorption peaks of N-H chemical bond are1485nm and1470nm, it is in the region of characteristic wavelength. The TN characteristic wavelength is1000.0～1398.6nm in compound fertilizer of ammonium nitrate as raw materials, and the characteristic absorptionpeak of N-H chemical bond in urea was1534nm and2210nm, it is out of the region of characteristicwavelength.�'�Interval PLS is a good way to select characteristic wavelength of P2O5in compound fertilizer ofammonium dihydrogen phosphate as raw materials, and the characteristic wavelength is1000.0～1696.3nm. The method of correlation coefficient is good to select characteristic wavelength of P2O5incompound fertilizer of calcium hydrogenphosphate as raw materials and the characteristic wavelength is1006.2～1127.9nm. The characteristic absorption peak of chemical bond P-H is1891nm, and P-OH1908nm, they are all out of the region of characteristic wavelength.�'�The result of model using characteristic wavelength is better than pan bands to determinenutrients content of compound fertilizers, which can help improving the accuracy of detection and reducingthe quantity of wavelength and model calculation.