A Detection Method for Soil Available Potassium Content Based on Capacitively Coupled Contactless Conductivity Signal

KeyWord:soil available potassium  contactless conductivity detection signal  Gaussian peak fitting  Levenberg-Marquardt(L-M)

Abstract:

      In this paper,a method based on the capacitively coupled contactless conductivity detection(C4D) signal was proposed for the rapid detection of soil available potassium content as many problems had occurred in the determination of soil available potassium content by traditonal methods,such as complex operation and long detection time.The Henan fluvo aquic soil samples were firstly characterized through high performance capillary electrophoresis with C4D device to obtain their C4D signals.Subsequently,the peak spectrums of the signals were identified by using derivative method and the Gaussian curve fitting method,then the peaks were filtered based on setting conditions.A model for single Gaussian peak was established base on Gaussian peaks,peak position,full width at half maxima and peak area of the Gaussian curve.Then Levenberg-Marquardt(L-M) algorithm was combined with the Gaussian peak fitting algorithm to optimize the characteristic parameters used to describe the information of C4D signal.The relational model between peak spectrum and soil available potassium content was established by the combination of the Gaussian characteristic parameters and partial least squares regression method(PLS),achieving the prediction of soil available potassium content.The experimental results showed that it was feasible to use the Gaussian peak fitting algorithm based on L-M algorithm combined with PLS method for C4D signal to determine soil available potassium content with high accuracy.The coefficient of determination(R2) was 0.856 4,and the residual predictive deviation(RPD) was 2.639.The method was suitable for the rapid analysis on content of soil available potassium.