A new modelling technique for root systems
is providing benefits across a wide range of
disciplines.
Image: iStockphoto

Root systems are notoriously difficult to study because they are hidden from view in the soil. At UWA, a three dimensional root architecture model called ROOTMAP is helping unveil the truth beneath the surface.

ROOTMAP was developed as a collaborative partnership between the Grains Research and Development Corporation (GRDC), the Department of Agriculture and Food WA (DAFWA), the Centre for Legumes in Mediterranean Agriculture (CLIMA), the UWA School of Plant Biology and the Tasmanian Institute of Agricultural Research (TIAR).
 
This model was designed to simulate the way that water and nutrient uptake and the growth of crop root systems respond to the changing soil environment. It has been used to investigate a range of agronomic problems from water and nutrient dynamics at the micro scale, up to field-scale situations of crop water and nutrient use over many seasons.

ROOTMAP was first created by Dr Art Diggle (DAFWA) and can generate any actual or theoretical root architecture and any number of soil resources. Those currently included are water, nitrate and phosphate.

The soil can be divided up into sub volumes of any size. At any point in space or time, information on local soil properties can be output. The number, length and type of roots each plant has in that local soil area can be shown, the amount of water and nutrient that each plant is taking up can be tracked, and nutrient uptake from fertiliser versus background soil sources can be distinguished.

ROOTMAP has been used to model pea root growth in response to changes in soil strength and phosphorus leaching in sandy soils. Another study has used it to model lupin and wheat root growth and nutrient uptake response to nitrate supply in the WA wheatbelt.

It was found to be a trade off between root depth and root length density for minimising nitrate leaching under lupin crops in free draining deep sands. It has also been used to investigate rooting traits and their contribution to competition between crops and weeds for water and nutrients.

“The strength of ROOTMAP is the capacity to investigate complex interactions between crop root systems and their below ground environment,” current research program co-creator, Dr Vanessa Dunbabin, from the University of Tasmania, says.

“Recent improvements to the graphical output capabilities of ROOTMAP have strengthened the capacity for it to be used as a visualisation, demonstration and teaching tool,” UWA Assistant Professor Michael Renton says.

“Currently we are working on further refining the visualisation and making a set of automatic analysis tools, which will greatly reduce the amount of time needed to analyse the complex output from the model, and compare it with available data.