Agricultural & Wine Sciences
CSU Rhizolysimeter
The Facility
- The CSU Rhizolysimeter is one of the Largest root growth and soil water research facilities in the Southern Hemisphere and is an important component of the EH Graham Centre for Agricultural Innovation a research alliance at Wagga Wagga between NSW Department of Primary Industries and Charles Sturt University.
The complex contains 24 intact soil monoliths(2.5m height and .74m inside diameter) encased in 6mm steel tubes. The encased soil monoliths are arranged in two rows of 12 in an underground laboratory which allows access to the side of the soil monolith from 0.6-2.5m beneath the soil surface.
- The design of the facility allows for non-destructive, high resolution in situ measurements on root growth and soil water dynamics. The soil monoliths can be fitted with a wide range of sensors.
- The rhizolysimeter has been structured to simulate crop growth in a phase garming rotation in order to investigate its impact on dryland salinity. An understanding of the root growth and water dynamics in the subsequent crop phase of a pasture/crop rotation would help to develop farming systems that reduce dryland salinity problems.
Instrumentation
- Root growth dynamics - each soil monolith is fitted with six minirhizolysimeters. Minirhizolysimeters are transparent 3mm thick Perspex tubes that allow visual monitoring of roots. The minirhizolysimeters are 3cm in diameter and have been installed horizontally at 20, 40, 65, 90, 145 and 205 cm depths. There are a total of 144 minirhizolysimeters. Analogue and digital image equipment allows for the capturing of root images for quantifying root dynamics in situ.
- Soil water dynamics - Seven TDR (time Domain Reflectrometry) sensors to measure soil water content are fitted to each soil monolith. The TDR are three-rod 30cm sensors connected to a Tektronix 1502C cable tester. The TDRs have been inserted at 15, 30, 55, 75, 105, 135, 190cm depths. The system is controlled by a Campbell Scientific data logger and 24 multiplexer units. There are a total of 168 TDR sensors, which have ben programmed to measure soil water content every 48 minutes.
- Crop evaporation fluxes - A portable, closed cylindrical chamber is used for rapid measurements of evapotranspiration fluxes. The chamber (120cmhigh, 80cm diameter) comprises an aluminum frame covered with Mylar film and fitted with two small rotating fans for mixing the air. A combined temperature and humidity sensor connected to a data logger allows for measurements of evaporation flux to be taken at one second intervals.
Research Projects
- 1999-2003; Sustainable rotations through recharge control by enhanced lucerne water uptake (GRDC Project UCS29).
Objectives
(1) to determind how lucerne developes its root system as influenced by soil type, cultivar and incidence of summer rainfall.
(2) To quantify water use by lucerne as a function of soil water distribution over the soil profile.
(3) To determind the influence of foilage removal on subsoil water use. - 2003-present; Sequencing crop rotations that best utilize biopores to control groundwater recharge and maintain dry catchments (GRDC Project UCS00003).
Objectives
(1) To determine, in relation to soil depth. how lucerne roots decay in soil and the stability of the remaining biopores.
(2) To determine how contrasting soils wet up in the succeeding crop phase of a phase garming rotation following on from a lucerne pasture phase.
(3) To Determine differences between crop species in their ability to exploit remnant lucerne biopores and to capture surface and subsoil water.
History
- The construction of the rhizolysimeter facility commenced in 1995 an was funded by an ARC Mechanism B Infrastructure Grant of $160,000. A further grant was obtained from the CSU Research Infrastructure Block Grant scheme of $30,000 to complete the instrumentation of the facility. The facility become operational in 1998.
Further Information
- Can be obtained from:
Associate Professor Phillip Eberbach
phone 02 6933 2830
fax 02 6933 2924
email peberbach@csu.edu.au