FARMERS in the habit of putting out gypsum regularly may be able to save costs by conducting soil tests to check whether it is required according to a Birchip Cropping Group (BCG) researcher.
Speaking at last week’s BCG main field day Tim McClelland said while farmers on heavy sodic clays would always get a response from the application of gypsum as a soil ameliorant, on other soil types where farmers were using gypsum for its sulphur component it may be possible to skip an application.
“Trial results across southern Australia have shown that while those using the gypsum as an ameliorant will always get a response, there were a number of sites, where putting in sulphur was the main priority, where there was not a statistical response to the application.”
“Getting a soil test can really help, you will see whether you will get a response from the sulphur or not.”
A straw poll of growers using gypsum at the day said while some used soil tests to decide whether to apply gypsum, others did it on a set rotation while others always applied it before the canola phase, with canola a greedy user of sulphur.
The use of gypsum is not cheap.
The gypsum itself normally works out around $15 a tonne, with application rates of around 2.5 tonne a hectare, freight costs from the gypsum pits in the northern Wimmera and southern Mallee cost many farmers in excess of $20/t, along with the spreading itself.
“It can easily cost $100/ha, so in years where cashflow is tight a test to see whether your soil really needs the sulphur could save you a lot of money,” Mr McClelland said.
He said farmers could also look at alternative forms of sulphur, such as sulphate of ammonia.
Mr McClelland also said farmers needed to know what they were put on.
“There’s a wide variation in the quality of gypsum in terms of its analysis, from the best quality Gypsum 1 grade to Gypsum 3. It pays to get a test from the gypsum pit you are using to see what quality product you are getting – even within the pit there can be quality differences in the product from different parts of the pit.”
“It’s a great product and for those guys on heavy sodic clays where it has two uses it is nearly always worthwhile putting it out, but for others it is a case of using it when you need it.”