OF ALL the indicators of farm health, few are as simple to measure yet as complex to interpret as soil pH.
High and especially low soil pH can severely limit plant choice and have a direct effect on farm production and profitability.
A soil scientist with the Victorian Department of Primary Industries, Doug Crawford, told a recent series of soil-health field days in Gippsland that testing soil pH was cheap and simple, but correcting an imbalance was not so easy.
"We are not always sure of the causative mechanism," Doug said.
He urged farmers to soil-test regularly to get an accurate indication of where soil pH was headed.
"One soil test tells you about the status, but it doesn't tell you how you got there or where you are going," Doug said.
"Two soil tests tell you about acidification and give you some idea of what to do."
Doug said the take-home message was to monitor pH movement.
"In pastures, pH doesn't change quickly so re-testing the paddock every five to 10 years should do, but do it more often in intensive agriculture such as horticulture," he said. Lime should be applied when needed and incorporated if possible.
A range of measures had also emerged the past 20-30 years on how to manage soil acidification.
These included rotating paddocks used for fodder production and feeding out, using urea rather than ammonium-based fertilisers and choosing perennials rather than annuals when sowing pasture.
"Tolerant species can also be used but this is avoiding the problem, not actually dealing with it," Doug said.
