Research On Rapid Measurement Model Of Nutrient Content And PH Of Compound Fertilizer And Liquid Fertilizer Based On Near-infrared Spectroscopy

Compound fertilizers and liquid fertilizers play an increasingly important role in the field of agricultural production in China.However,the counterfeit phenomenon for products in the fertilizer market is becoming more and more serious,which not only seriously damages the normal order of the fertilizer market and infringes the interests of consumers,but also destroys the agricultural production.The analysis method of Near-infrared spectroscopy has the characteristics of goodreproducibility,rapidity,accuracy,and low cost.It is believed that it will play an important role in the quality control of the fertilizer production process and market supervision of the fertilizer product quality in the future.This paper takes 120 kinds of commercial compound fertilizer samples and 100 kinds of liquid fertilizer samples in the mainstream market as the research objects,and uses Fourier near-infrared spectroscopy analyzer（Antaris?II FT-NIR）to collect the near-infrared spectra of commercial compound fertilizer samples in the interval of 10000-4000.cm^-1and the liquid fertilizer samples in the interval of 10000-6000 cm^-1.The quantitative models of the near-infrared spectroscopy and various indicators for commercial compound fertilizers and liquid fertilizers,including p H value,the content of nitrogen,phosphorus and potassium,are established by the different calibration set selection methods（SPXY,KS）and multiple multivariate calibration regression methods（PLSR,PCR,SMLR）combined with various preprocessing methods（MSC,SNV,1st D,2nd D,SG smoothing,ND smoothing）and different characteristic spectrum selection methods（GA,SPA）.For the nitrogen content of compound fertilizer,the model obtained by the SNV+1^stD+SG-SPXY-SPA-PLSR method is better than the model established by the other methods（Rp=0.9497,RPD=4.59）.The optimal model for the phosphorus content of compound fertilizer is established by the method of MSC+1^st D+SG-SPXY-GA-PCR（Rp=0.9675,RPD=4.89）.The optimal model for the potassium content of compound fertilizer is built by the method of SNV-SPXY-GA-PLSR（Rp=0.9348,RPD=3.55）.The optimal model for the p H value of compound fertilizer is obtained by the method of MSC-SPXY-GA-PLSR（Rp=0.9457,RPD=2.88）.According to the model evaluation criteria,except for the pH model that needs to be further optimized,the other models can be used for rapid test.For the nitrogen content of liquid fertilizer,the model obtained by the method of 2^ndD+ND-KS-GA-PLSR is better than the model established by the other methods（Rp=0.9682,RPD=4.24）.The optimal model for the phosphorus content of liquid fertilizer is built by the method of 1^st D+ND-SPXY-GA-PCR（Rp=0.9784,RPD=4.35）.The optimal model for the potassium content of liquid fertilizer is obtained by the method of SG-SPXY-PLSR（Rp=0.9357,RPD=3.27）.The optimal model for the p H value of compound fertilizer is established by the method of 1^st D+SG-SPXY-GA-PLSR（Rp=0.9358,RPD=3.14）.According to the model evaluation criteria,these models can be used for quick test.