August 21, 2013
A new soil management tool will give farmers a deep understanding of their soils and the management practices needed to reach their productive potential says the Department of Environment and Primary Industries (DEPI) soil specialist Declan McDonald.
Mr McDonald recently held on-farm training at Berrybank to demonstrate the use of the Visual Soil Assessment (VSA) tool.
“The VSA is a hands-on method that cleverly pulls together the basic elements of good soil management into an easy-to-use evaluation tool that allows farmers to score their soil condition, and pasture or crop condition,” he said.
“The elements of the soil assessment part of the VSA include soil texture, structure, porosity, colour and smell. It also includes earthworms as a surrogate for biological activity.
Mr McDonald said the VSA manual guided landholders through a process that assigned a score for each soil property. Scores were tallied to reflect the overall quality of the soil.
“A similar process is followed to assess pasture or crop condition using indicators such as pasture diversity, colour, density and weediness and ideally there should be some alignment between the soil score and the plant score.
“A significantly higher plant score suggests that production is heavily reliant on application of fertilisers, while a higher soil score suggests the productive potential of the soil is not being realised,” he said.
Mr McDonald said the VSA would appeal to farmers because of its accessibility and ease of use.
“Perhaps the most interesting aspect of the tool is the ‘drop shatter test’. As the name suggests, a cube of soil is dug intact from the ground and is then dropped from waist height onto a hard surface three times.
“The shattered soil is then arranged by aggregate size onto a small sheet (see photo) and compared to soils of varying quality as shown in the manual,” he said.
“This very clearly indicates how well a particular soil is structured and represents a powerful learning opportunity for participants as well as a benchmark against which future soil improvements can be measured.”
Mr McDonald said the VSA also comprises environmental assessments that allow farmers to understand the relationship between good soil management practices and the potential for carbon sequestration, risks associated with greenhouse gas emissions, or nutrient loss off-site.