The complexities of nutrient budgeting tool Overseer are being broken down for farmers as the computer programme quickly evolves from an aid to becoming an integral part of land and water regulation in New Zealand.
The owners of the programme, AgResearch, the Ministry of Primary Industries and the Fertiliser Association of New Zealand, have formed Overseer Management Services and appointed a new general manager, in recognition of the modelling system's growing importance.
"There are a lot of farmers who've been using it for a while now, and fertiliser companies have been really using it as a big part of their ability to advise farmers, so it's been around for a while, but it becomes much more visible when regional councils start using it in their planning," said general manager Caroline Read, who was appointed in November.
"We're in a big state of change, where we're actually having to think about how we contribute to the quality of the water in New Zealand."
First developed in the 1990s, Overseer has steadily evolved as a nutrient budgeting tool, becoming ever more complex. It is able to calculate loss of nitrates to water, phosphate runoff and greenhouse gas emissions from nine farming systems, including dairying and arable farming.
"It did start off as what's called a block scale piece of software. It did one specific activity on one specific piece of land, and it's developed to being much more complex and much more wide- reaching," Read said.
"It now does a whole farm system in one go, and what it does is look at all the nutrient flows in that farm system, and it tells you what your nutrient budget is - which, in essence, tells you what your losses of nutrients are from your farm."
Under the Canterbury Land and Water Regional Plan, farmers will be expected to use Overseer to calculate how much nitrogen will leach from their farms into groundwater. If levels are too high, they will be expected to modify their farming practices.
"Regional councils can use Overseer data to give them an idea about what is practical or what is possible off different farming systems, so it can give them an idea of what is happening within a region, but it can also give them an idea of what the potential is," Read said.
"It can tell you what the budget will be from just a basic management practice process, and what the budget will be from a better management practice process. It can tell you that at the moment, you might be losing a certain amount but if you did a few different things, you'd be losing less."
Overseer is complex, and although it is free to download, it requires some expertise to use.
"There's hundreds of different data entry things that are needed for your specific case, and there are foundation sets of data like soil data and climate data, but you do need to put in your farm- specific information about stock numbers and how they're moved about on the farm," Read said.
Foundation of Arable Research senior manager for research development Roger Williams said that while Overseer still needed work to make it applicable for arable farmers, it was becoming an essential tool for both farmers and regulators.
"I think Overseer has moved from being a useful nutrient budgeting tool for the pastoral sector into a model of national significance in a regulatory context.
"It's moved in 18 months or two years from one to the other. It's been incredibly rapid, the speed at which its significance has grown, and I think, to be honest, that's taken everybody a bit by surprise."
To help spread the word about Overseer, a new communications strategy is being developed. To ensure consistency in the way Overseer is used, best practice data standards were released late last year.
"They're to help the experts who run Overseer budgets make sure they're defining all of these complex aspects of different farming systems the same," Read said. "The better data you've got, the better those estimates are going to be out the end of the model."
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