Advanced time-lapse imaging of soil-water dynamics
The volume of water contained within soil is fundamental to agriculture because it significantly affects the growth of plants. Unfortunately, the universally accepted method for estimating soil water content (the thermogravimetric method) is labour-intensive and time-consuming to use for field-scale monitoring, taking 24 hours to sample the soil and measure the loss of water.
These tools provide information which is invaluable to those who hope to gain a more in-depth understanding of water systems delivery and water uptake by plants, assisting with more effective irrigation practices
Dr John Triantafilis, Senior Lecturer, BEES
In order to improve the efficiency of measuring and monitoring soil water content, a number of moisture sensors have been developed for use in the field, including commercially available neutron and capacitance probes, time domain reflectometry and wireless soil moisture sensor networks. To add value to the data collected at these point locations and estimate soil water content along the entire transect, geophysical tools such as direct current resistivity (DCR) instruments can be used. However, they too have their limitations.
“DCR instruments require a large number of contact electrodes to be physically installed in the ground,” said Dr John Triantafilis, Senior Lecturer at the UNSW School of Biological, Earth and Environmental Sciences (BEES).
“Subsequently, a large amount of time is needed to take the necessary measurements to make an electrical resistivity image from appropriate software,” said Dr Traintafilis.
An alternative and far more efficient approach has been developed by Dr Triantafilis and Mr Jingyi Huang from BEES, in collaboration with Professors Budiman Minasny and Alex McBratney from the University of Sydney.
In their collaborative research, a state-of-the-art electromagnetic induction instrument (DUALEM-421) was used to collect information on the apparent electrical conductivity of soil, at various depth increments, in a field growing lucerne.
Using this instrument, and cutting-edge inversion modelling software (EM4Soil), the researchers were able to correlate estimates of soil conductivity with measured soil water content from a bank of soil moisture sensors located at 8 different locations across a field irrigated with sprinklers, demonstrating that it is possible to accurately measure, model, map and monitor soil water status in real time.
Dr Triantafilis and his colleagues are excited at the potential application of their research, for farmers and researchers alike.
“These tools provide information which is invaluable to those who hope to gain a more in-depth understanding of water delivery systems efficiency and water uptake by plants, assisting with the implementation of more effective irrigation practices.” said Dr Triantafilis.
This research was unfunded but was supported in the field by Mr. Robert Paul Lipscombe and Mr. Glen D Foxwell (The University of Sydney) and Mr. Ehsan Zare, Mr. Mudasar Muzzamal and Miss Claire Dennerley (UNSW Australia).
Banner image (top): © Gregory Heath - CSIRO. [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
