There is a strong social-licence angle in pursuing environmental efforts on water quality and greenhouse gases.
Farmers being seen to be making efforts across both areas will only aid farming’s continuing acceptability to society, regardless of the science dynamic.
“It really has to pass the front page test now,” Dewes said.
She has compiled a matrix of management options that hit the right notes for lowering nitrate losses in waterways and lowering gas emissions.
They include lower stocking rates, doing away with winter grazing, lower nitrogen fertiliser and greater reliance on mixed forages and legumes.
There will also be very few farmers who will argue against planting more trees that help reduce a farm’s gas footprint.
Just getting all farmers to compile farm environment plans, as required under water and greenhouse gas proposals, will be a good start.
“As they come to understand their businesses better they can question some of the things they are doing on specific parts of the farm. For example, why am I walking my cows up this steep section, just to harvest 4t drymatter every year? It may be better in trees and more profitable.”
Dewe’s modelling has shown there are significant profits to be made by making integrated changes to reduce waterway nitrates and gases in tandem.
In her best case, farm operating profit is up 48%.
However, she maintains a reduction in stocking rates, the single biggest driver of both nitrate losses and gases, still has a long way to go nationally.
“There has been so much noise about the impact of lowered stocking rates on profit when in fact you take a lot of stress out of the system.”
Her modelling indicates a drop of 18% in stocking rate delivered a 14% increase in per cow production.
“But it seems looking around the country cow numbers are staying about the same, when some areas could drop by 15%.”
DairyNZ has a dozen commercial dairy farms involved in its Partnership Farm Project, studying the effects of lowering dairy farms’ nutrient losses to waterways and gas footprints.
So far the results of only one, Owl Farm at St Peters School near Cambridge, have been released.
They highlight the relationship between lowering gases and waterway nitrate losses and support the options Dewes has presented.
Changes to management have included halving bought-in feed, a 5% lower stocking rate and greater on-farm cropping.
All served to lower nitrogen losses to waterways by 14%, cut gases by 1t a hectare to 12.5t a hectare and ultimately lift farm operating profit by 14%.
A DairyNZ spokesman said the Government’s initiative to require all farms to have a farm environment plan containing a greenhouse gas component will provide the industry with a meta data source.
Analysing that data will grow knowledge of managing links between waterway nitrates and greenhouse gases including nitrous oxide.
“If you can measure this data you can monitor it and ultimately you can improve it.”
