ON THEIR notoriously wet dairy farm in South Gippsland, Tim and Grit Cashin often apply nitrogen generously in the hope that it will last a bit longer in the system - and trigger extra grass growth.
In reality, much of that nitrogen might be not be used, and further losses occur if it is not being applied straight after grazing.
It may well be a mindset other farmers in the region follow, but Richard Eckard, who is the associate professor and director of the Primary Industries Climate Change Centre at Melbourne University, said Australian dairy farmers needed to get out of this habit.
Speaking at a GippsDairy Focus Farm field day on the Cashins' leased property last week, he urged the crowd of 100 producers to change their mentality when it came to nitrogen use.
"I think what's happened over the years is that some people have started to apply more and more nitrogen, and they've become dependent on it," Mr Eckard said.
"They are also feeding out grain at the same time, when they should really be making sure the cows are eating the extra grass grown from the nitrogen."
He said dairy farmers need to plan carefully for the additional growth in the paddock, and ensure that grass was consumed.
"Often what you will see is that farmers don't adjust their grazing management. They need to allocate cows to a smaller area to consume that extra grass," he said.
Mr Eckard said the biggest issue with nitrogen was it was "slippery" - and could be lost easily to the environment.
"It can be lost as a gas…or it can run off with water," he said. "Probably only 30-40 per cent is used by the cow."
But Mr Eckard had some useful advice to help farmers change their mindset about nitrogen.
"If you put nitrogen in your feed budget, rather than your fertiliser budget, you will start to think about applying it in the right way," he said.
Farmers also needed to consider the fertility of their soils and pasture, when taking into account what response the nitrogen would have on their pasture.
"If your base fertility is good, you will capture a lot of the nitrogen, but if your soil fertility is lacking and you have a poor pasture composition, then you won't get much of a response," he said.
Once farmers have established the fertility of their soils, Mr Eckard the next thing to consider was the temperature.
"When you are trying to predict when to start nitrogen applications, look back at the season you've had. "If you've had a dry season, there will already be nitrogen in the soil. If it's been wet, there will be less nitrogen."
He added the main reason best practice guidelines recommended nitrogen be applied immediately after grazing was because once rapid regrowth began, that was the time the grass utilised nitrogen.
"If you delay 14 days in putting on your nitrogen, the response is decreased by 14 per cent," he said.
Mr Eckard said he understood many farmers could not apply nitrogen straight after grazing, but they had to understand that putting on a lot of nitrogen two weeks after grazing would not have a powerful impact.
"This is the compromise you are making," he said. "Farmers need to know that the best time to put nitrogen on is straight after grazing…there is a small window."
After Mr Eckard's presentation, dairy farmer Tim Cashin said his view about nitrogen use had changed.
At the moment, the Cashins' 270-head milking herd were on a 50-day rotation and produced about 529 kilograms of milk solids per cow, with 2.23 tonnes of grain fed out per cow.
Nitrogen use equated to 288kg per hectare, with 8.7 tonne of dry matter consumed on-farm and roughly 10-11t grown. Mr Eckard advised this application rate was slightly high, considering how much dry matter was grown.
"I think we will try and be more flexible now," Mr Cashin said.
"We often put on extra urea if it looks like it is going to be wet, because we thought it would stretch it out further, but that's just not the case.
"Instead - we might try to put on smaller amounts more often. Economically, this might cost us more, but I thought a good idea would be to go in with a neighbour, and share the truckload."
However in reality, this practice might be easier said than done.
"When it's really wet, the truck can't physically get on the farm," he said. "But this is the trade-off we have to make. The longer you leave it, the bigger the losses will be."
And while the Cashins might be thinking differently about nitrogen now, he said they did try to make sure the herd was consuming the extra grass grown from nitrogen.
"We do a reasonable job at this, and we strip graze."
They had also made an investment into "humping and hallowing" the wet areas of their farm to decrease nitrogen run-off.
Restrictions could come in the future
WHILE Australian dairy farms are yet to face any limitations on nitrogen use, it's become the norm in other countries.
"In Germany they can't use more than 170 kilograms of nitrogen per hectare, and that's from all sources…that could even come from legumes," Richard Eckard (pictured) said, who is the associate professor and director of the Primary Industries Climate Change Centre at Melbourne University.
Speaking at a GippsDairy Focus Farm field day in Leongatha South last week, Mr Eckard warned the crowd of 100 farmers that the situation could change in the future if overseas customers of Australian dairy products demanded restrictions as proof the country was "clean and green".
"There is a problem in Australia and it is a concern. We are getting away with it at the moment, but it might come back to bite us," he said.
"The big difference in countries such as Germany or New Zealand is they have wall-to-wall dairy farms, so the impact of using too much nitrogen can be seen in the water."
But Mr Eckard was also confident that Australian dairy farmers were becoming more aware of applying nitrogen appropriately.
"When I started researching nitrogen a couple of decades ago, people were not concerned about the environmental damage," he said.
"But today, people are asking questions, and that in itself is proof that attitudes towards nitrogen are changing."