Fast determination of contents of nutrients and stone powder in compound fertilizer using near infrared diffuse reflectance spectroscopy

In the present paper,a new approach to fast determination of contents of nutrients,including total nitrogen content(N),P2O5 content(P) and K2O content(K),and of stone powder content in compound fertilizer composed of urea,ammonium dihydrogen phosphate,potassium chloride and stone powder was proposed using near infrared diffuse reflectance spectroscopy.PLS models of N,P and stone powder content were built with the SEP values of 0.8,0.8 and 1.4 respectively.The information on which stone powder content model was built is the spectrum of crystal water existing in stone powder.K content was calculated using other ingredientcontents by normalization principle with a SEP value of 1.5.Although the SEP values are a little larger than the reproducibility errors of the GB/T methods which are conventional methods,the new method can be accepted by situ quality control in the production process of compound fertilizer.