EXPECTED demand for nutrients is just as important as the available supply in the soil when budgeting for the next crop, and grain growers in Western Australia are being urged to get good advice prior to planting.
Calculators are available through the Grains Research and Development Corporation (GRDC), including a computer software package called Lime and Nutrient Balance which evaluates eleven nutrients and lime in relation to 25 agricultural products.
GRDC is also currently funding several projects to improve the tools available to growers and to develop new ones, including one to determine nutrient loss through factors such as leaching.
For most growers, though, soil testing and analysis by experts will be the most effective system, according to Bill Bowden, research officer with the Department of Agriculture and Food (DAFWA).
“It’s good to get into a routine of testing this time of year. You don’t have to test the entire property – we recommend about one-fifth every year to build up a good overall picture and monitor trends,” Dr Bowden said.
“Wherever you get the advice, make sure they are using locally based calibrations. Recommendations based on interstate or overseas data will not properly take into account the impact of the local environment.
“The other key is to estimate yield, not just what nutrients are available in the soil, to get both sides of the demand and supply equation.”
While a lot of farmers simply do what they did last year, with little or no impact on profitability because that’s often insensitive to the amount of fertiliser used, Dr Bowden says you’re better off knowing the state of your nutrients.
“Most people take a hard look at nutrient budgeting when things change dramatically, like successive years of drought, a spike in fertiliser prices or a drop in grain prices.
“In most cases, the season comes over the top of any difference in inputs and will make the biggest difference in the end to things like yield.
“But getting the balance wrong can have an impact on segregation and grades, and over time you may end up with a problem if you don’t catch it early,” Dr Bowden said.