Digital interface device for field soil hydraulic conductivity measurement

Abstract

Accurate and reliable measurements of field-saturated hydraulic conductivity (Kfs) are essential for accurate determinations of soil and solution water fluxes. Kfs is a crucial parameter to design drainage, irrigation systems and many other environmental, agricultural and industrial installations Reynolds et al. (1983). There is a high demand for Kfs data. Its evaluation is preferable to be done in situ. A popular device to measure the Kfs is the head well permeameter such as the Guelph Permeameter. However, it is an analog equipment based on a Mariotte’s bottle that requires full attention and training to be manually operated, where the reading of the flux values (Q, in cm3/min) is time-consuming and costly. In this paper, we describe a device, with a digital readout, to measure the steady state rate of water level change Rs, in order to obtain Qs and Kfs. The method is based on the monitoring of the vacuum variation of the Mariotte’s bottle. Our results show no statistical differences between the measurements values of manual and automatic recording using paired t-test. In addition, our device identifies measurement artifacts due to the variation of the ambient temperature during measurements. The necessary accuracy for the digitalization method becomes feasible due to the availability of accurate piezoelectric transducers (Micro-Electro-Mechanical System – MEMS). Automating and digitizing these processes will reduce time, costs and increase the accuracy and availability of data. The device can be directly adapted to commercially available head well permeameters as shown in our experimental results. The more widespread use and understanding of this parameter can improve the rational use of water for irrigation and use in risk models for forecasting available soil water and therefore crop productivity.