Abstract
Feasible calibration methods are required for the application of commercial sensors to field monitoring of soil water content and solution concentration. Simple in situ calibration methods for the 5TE sensor are proposed for the estimation of soil water content (θ) and 1 : 5 soil to water extract electrical conductivity (EC1:5). θ can be obtained from 5TE sensor readings with a correction fac-tor C, which is available from several soil samples taken during monitoring. EC1:5 can be obtained from a linear function of soil pore water electrical conductivity (ECp). ECp is derived from 5TE sensor readings using the Hil-horst equation, and the gradient and intercept of the linear function are also calculable from a small number of soil samples taken during monitoring. The proposed calibra-tion methods were applied to monitoring of θ and EC1:5 in a tomato field under drip fertigation, and the efficacy of the methods was confirmed by comparison with methods using conventional lab-based calibration.
