Summer crop growers are being encouraged to take a simple test this harvest time to uncover precise, paddock specific data on nutrient removal.
Bede O’Mara, agronomist with Incitec Pivot Fertilisers based in Toowoomba, said grain nutrient testing was available on all summer grains and was a quick and easy way to see how much nitrogen, phosphorus, potassium, sulphur and zinc were leaving the farm with the grain.
“Our summer crop seasons have been anything but average over the last few years, so why rely on published averages for nutrient removal, when you can have actual data from your own crops?” he asked.
Mr O’Mara said grain test results from the last three years of summer crops revealed wide variations in nutrient removal levels depending on the season.
“It might be easy to just use an average figure and assume that 18 kilograms of nitrogen is being removed per tonne of sorghum grain, but grain test results from my trials show the actual nitrogen removal figure could be up to 100 per cent higher,” he said.
“Grain nutrient tests have also revealed that the rate of potassium removal from my sorghum trials has been much higher than the recognised published average of 3.3 kilograms of potassium per tonne of grain, at between six and 10 kilograms of potassium per tonne of grain.”
In phosphorus results, his grain testing in sorghum shows instances of both higher and lower phosphorus removal than the recognised average of 3.4 kgP/tonne grain.
He added that grain tests would also provide grain protein results, while other quality parameters like test weight, screenings and moisture are tested at the point of sale.
“The grain protein level reveals a lot about the effectiveness of the nitrogen strategy for grain sorghum, as it does with many cereal crops,” he said.
Mr O’Mara said grain testing was as simple as collecting 400 grams of harvested grain from the back of the header, truck or silo and submitting it to the laboratory for analysis.
The Nutrient Advantage® laboratory offers grain testing on all summer crop varieties, using quality assured testing procedures.
“Your local fertiliser adviser can help you organise grain testing and analyse the information to calculate nutrient export data on a paddock by paddock basis,” he said.
“Grain testing doesn’t replace the need for soil testing, but it does provide a very useful base for planning for the coming season and optimising spending on replacement nutrients.”