Calibration of two neutron probes in field and laboratory conditions

Abstract

Two different methods were used to calibrate two neutron probes: model CPN 503DR which measures soil water content and CPN 501DR for soil density and water content. The use of drums to hold the soil in the calibration of neutron probe in laboratory condition was appropriate for high clay-content latosol. For low clay-content latosol, a loss of neutrons through the drums was detected. The linear regression equations, determined in both on-field and laboratory conditions for high clay-content latosols, presented slope coefficients similar to the one provided by the manufacturer which, though not determining the real value of soil water content, may be useful to detect the variations of water content in the field. The model CPN 501DR showed lower sensibility to determine the soil water content than the model CPN 503DR.