Mine manager Antony Stodart says that the material is dug out and put through two crushing processes to form a coarse powder that is stockpiled prior to trucking to a bagging plant. Samples are taken regularly for testing to ensure that the humate is up to specification. About 1,000 tonnes are processed annually, which makes it a minor product compared with the 320,000 tonnes of lignite coal the mine produces.
David Whitteker who is managing director of Humate Solutions Ltd, distributes humates to fertiliser companies and other wholesalers. He says that the New Vale product is around 65% carbon and a very good source of humic and fulvic acids.
“When humates are mixed in with fertilisers like lime, urea and phosphate they act as an excellent food source for fungi and bacteria and assist in breaking down the fertiliser into soluble forms so nutrients are more easily taken up by plants.”
“The carbon is in the form of carbohydrate and some farmers feed it to their cows at a rate of 50 g per day and it is said to improve ammonia retention in the rumen and absorb toxins.”
David believes that farms can maximise the value of conventional fertilisers by mixing in humates to reduce leaching of nutrients. Microbial activity is also stimulated and this has the effect of unlocking nutrients and making them more available.
“There is a lot of phosphate in the ground already that farmers have applied over the years but it is bound up and unavailable. Using humates results in the release of this phosphate making it available to plants. A year after putting humates on, you can usually detect an increase in available phosphate,” he says.
“It is also very good for locking up heavy metals – superphosphate contains cadmium that is accumulating in soil, and we have done trials with Solid Energy mixing 2 – 3% of humates in with phosphate and it actually locks up the cadmium so that it doesn’t appear in plants or waterways.”