With several governments around the world pursuing limits on nitrogen fertilizer use in agriculture, how would farmers adapt if the Australian government took a similar approach?
Key points:
- Fertilizer production and use is responsible for more than half of the greenhouse gas footprint of the domestic wheat crop
- Nitrous oxide emissions come from the volatilization of nitrogen fertilizers such as urea
- Volatilization can be minimized through management, but synthetic nitrogen is difficult to replace in cropping systems
Birchip Cropping Group senior research director James Murray said the obvious way to reduce nitrogen fertilizer emissions was to use less.
“I guess naturally the preferred option is to grow more legumes in the rotation, because when we grow legumes we don’t need to apply nitrogen to meet production,” he said.
“But it’s not as simple as that, because there are emissions of greenhouse gases like nitrous oxide associated with the decomposition of legume stubble.”
Fertilizer production and use accounted for 58% of the greenhouse gas footprint of Australia’s wheat crop over the past five years, according to the Department of Agriculture.
Of this, 31 percent occurred on the farm, much of which was caused by the volatilization of nitrogen fertilizers, where nitrous oxide is released into the atmosphere.
Nitrous oxide is a greenhouse gas that is almost 300 times more potent than carbon dioxide.
Regardless of the motivating factors, more efficient use of fertilizers will benefit both the environment and your hip pocket, James Murray says. (Rural ABC: Angus Verley)
Aside from growing more nitrogen-fixing legumes to reduce fertilizer use, Murray says there are products available to slow the process of volatilization, which occurs when nitrogen is applied to a crop and there isn’t enough rain after the application to break it down.
“There are a couple of products on the market: one is a urease inhibitor, which reduces the risk of volatilization by delaying the release when applied if you don’t get a relatively quick follow-up rain,” he said.
“The other is a polymer coating, which slows down the release of nitrogen quite significantly.
“But the challenge with them is that they’re not necessarily cost-effective to use, because urease inhibitor retails for about $50 a ton on top of your cost of urea, so it opens up a question of the profitability that is in agriculture. system.”
Murray said whether or not farmers used a urease inhibitor, there was significant value in applying nitrogen correctly and minimizing volatilization.
“We talk a little bit about the four Rs, so the right rate, the right product, the right source and the right time, which at the end of the day will have significant benefits for production and if we reduce our greenhouse gas. footprint at the same time, that’s an advantage,” he said.
Countries like New Zealand, Canada and the Netherlands are pursuing limits on fertilizer application to reduce emissions, which Mr. Murray says it’s a consideration for farmers here.
“There are market access considerations and potential future mandates on how things are used,” he said.
“I think there’s a huge opportunity for the Australian grains industry to be ahead of the game on these things, whether it’s market access or potential mandate considerations.
“In terms of improving how we use our inputs, the biggest benefit is the bottom line in terms of improved crop production.”
Urea can release nitrous oxide into the atmosphere. (ABC Wimmera: Andrew Kelso)
What are the alternatives?
Some farmers are testing alternatives to synthetic fertilizers under the broad umbrella of “regenerative agriculture.”
Among them is Luke Batters, who farms with his family near St Arnaud in western Victoria.
“Our operation is largely a synthetic-based system and our use of synthetic fertilizers and chemicals has increased substantially,” he said.
“I was working in agriculture for seven years and when I came back to the farm I had a different mindset and so we’re trying some different things around inputs, in terms of how different carbon-based inputs affect and biological and chemical. the system.”
Mr Batters is testing alternatives such as compost, manure, seaweed and vermicast, which is a mix of products including worm parts.
“It wasn’t until I started doing this test work that I realized how dependent we were on nitrogen as a synthetic input,” he said.
Patches of nitrogen-rich sheep urine grow much better than the surroundings of Luke Batters’ farm. (Rural ABC: Angus Verley)
What are the problems?
Batters said that while he thought his trials were otherwise healthy, they were severely deficient in nitrogen and he hadn’t been able to make up the shortfall with the alternatives he’s used.
“I pretty much went cold turkey and stopped using synthetic fertilizers and it’s been pretty stark, the difference between synthetic fertilizers applied and no synthetic fertilizers and having to rely on those alternatives,” he said.
“These things will work in a system once the biology gets up and going, but because our current system is so depleted of biology, it hasn’t really taken off.”
Batters said he hadn’t gotten the results he’d hoped for, but he’d persevere.
“If there are regulations in the future about what we can and can’t do and we don’t have an alternative, we’ll be off the hook,” he said.