It might take five years or so but Bridgit Hawkins thinks New Zealand farmers might find the answer on their mobile phones.
In those phones will be data amounting to savings, for example, of at least $15,000-$30,000 a year for a 200ha irrigated dairy farm.
Ah, but if that's the answer, what was the question? Hawkins, chief executive of Regen, says it is this: How can farmers use effluent, nitrates and irrigation effectively to increase profits?
It's a big deal for most farmers; effluent management is no easy issue. Apply when the soil is too wet and it runs off. Apply when it is too dry - and it also runs off.
Applying nitrates has the same kind of efficiency and environmental concerns. Used correctly (and it can be devilishly hard to get it right) and it helps things grow. If not, it can be a pollutant - and has grown to be a community, political and environmental issue.
It's the same with irrigation. Often blamed for washing harmful substances into lakes and rivers, irrigation is a tremendous tool for farmers - but there can be a lot of negatives in with the nutrients, like leaching.
Which is where Regen comes in. It has devised an ingenious system of digital sensors sited on a farm, measuring elements specific to that farm like soil moisture, temperature, weather conditions and other factors; an algorithm clicks into action and delivers to the farmer a daily or five-day recommendation on how much irrigation, effluent or nitrates should be applied.
It's delivered over the mobile phone - every bit the farmer's constant companion these days as much as a tractor or dog - or a desktop.
Hawkins says Regen's three products take the guesswork out of this kind of management for more than 200 customers nationally.
"Our biggest product is still the effluent management," she says, "but I think that will change by the end of the season; the irrigation product will become biggest."
Driving the uptake is farmer response to environmental concerns about water quality and leaching of nitrates from farms, particularly dairy farms. Canterbury is leading the way, says Hawkins, with the regional council insisting farmers have a farm environment plan which covers four distinct areas - one of them irrigation and water management.
"Good management defines that, every time farmers want to irrigate, they know the soil has the capacity to hold the water being applied," she says.
Canterbury is the national leader in the farm environment plan stakes, with many other regional councils watching carefully as they decide on how to structure their own such plans.
A key element is that farms are often environmentally audited - and farmers can use the Regen data to demonstrate clearly they have been irrigating, spreading effluent and managing nitrates responsibly and effectively.
"I would say that in the next five years, most dairy farms will have something like this - and of course we want it to be this product that we have developed to lead the market," says Hawkins of the Regen irrigation product.
"It's very hard to quantify these things but if a farmer is over-irrigating, for example, we can affect that in a specific farm - and the farmer will save money on power, which can be a significant cost to get the water to the pastures it is meant for.
"If we get the soil to an ideal moisture level, that means more and better pasture, more and better milk and less need for farmers to buy in feed. So, while it is difficult to apply a broad financial benefit brush to it, we estimate that the difference to a 200ha irrigated dairy farm will be in the region of $15,000-$30,000 [in reduced costs/greater profits] a year."
That is hardly chicken feed. Hawkins also points to growing consumer concerns about sustainable farming and products and says that, internationally, consumers are starting to measure the amount of water used in products.
"People used to talk about carbon miles...now they are starting to talk about 'water miles'," she says, "and the industry has to take notice of that."
Regen is not standing still in the innovation game - it is looking at applying its irrigation service to crops as well as pasture, possibly brassica, maize and barley. It is also looking at international markets like India, the US and South America, a logical step for some home-grown Kiwi ingenuity.
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