Spotlight on Belah soils by Denys Slee

NSW Agriculture agronomist Graeme Mcintosh inspects field pea growth at trial site

FARMERS AND researchers associated with the award-winning Mallee Sustainable Farming Project (MSFP) have taken on a new challenge — to better understand the properties and capabilities of Belah soils.

These are one of the principal soil types covering thousands of hectares in the western NSW section of the project.

"The focus paddock module of the MSFP, which intensively monitored 50 farmer-managed paddocks across the project area within NSW, Victoria and SA, identified that mallee soils are not just mallee soils," said David Roget of CSIRO Land and Water.

"There is huge variability between the different soils' ability to store and hold water against evaporative loss, and to mineralise and hold nutrients against leaching," he said.

"In order to optimise the management of these various soils, the nutrient and water dynamics need to be understood."

First cab off the rank for a closer look are the Belah soils. They are found in 175 mm growing-season average rainfall country; the alkaline soils are heavier than those normally associated with the 'Mallee'; fallowing is a traditional practice among the increasing number of farmers in the area; and high-protein hard wheat is the principal crop grown.

Core trial site

A core trial site has been established at Kerribee, northwest of Mildura, and is being collaboratively managed by Belah Grain Growers, CSIRO Land and Water, and NSW Agriculture.

"Other core sites in the project, which are on sandy soils, are showing that fallowing doesn't provide a moisture advantage and that the opportunity cost of having a fallow in a rotation is high," said Graeme Mcintosh of NSW Agriculture, Dareton.

However, "farmers involved with the Kerribee project say they know that fallowing works on Belah soils. They want to find out why and if things can be done better. Producers are fallowing in the area to maintain moisture through weed control. They are mostly going to chemical fallows, although some prefer mechanical fallow for Rhizoctonia control."

Mr Mcintosh said work began at the core site last year and, when available soil-moisture measurements were taken in June 2002, the conventionally cultivated, long fallow treatment at the site had the most moisture.

At the other core research sites, intensive cropping has provided significant benefits through improved nutrient availability and retention. These improvements come from greater microbial activity because more root and top residues are returned to the soil. The potential for these benefits in Belah soils will be assessed.

Research at Kerribee also includes the assessment of break crops such as peas, canola and lupins and various rotations including fallow-wheat; pasture-wheat; continuous cereal; cereal-pulse; cereal-canola and opportunity cropping.

Other trials will focus on seeding preparation treatments such as district practice, direct drilling and reduced tillage; zinc treatments by treating the seed, by applying zinc in fertiliser or by spraying it onto crops; seeding rate experiments; and trials with balansa clover and lucerne.

Program 4 Contact: Mr Graeme Mcintosh 03 5027 4409 Dr David Roget 08 8303 8528