By: Alison Dewes
Good news, the New Zealand dairy herd has reduced by 100,000 cows according to the latest data. It would appear if there was
no more new expansion, the national herd may have reduced by 2%.
With nutrient constraints, and palm kernel use being tightened over time, awareness by good farmers that more can be gained from less, is emerging.
In different catchments under pressure like Rotorua Lakes for example, farmers that are getting on with the change have
dropped cow numbers progressively, removed winter cropping and many are using less nitrogen fertiliser without any total loss in productivity.
Where Overseer is used as a regulatory tool and N output has to drop, there is a constraint that the farm system changes have to be measurable by Overseer to
demonstrate a net benefit.
Things like lower stocking rates, less N fertiliser, less or no winter cropping, standoff areas with good effluent disposal, and
changes in stock policy are all things that are readily measurable by Overseer and are observed by regional councils.
It is probable that stocking rates in some catchments will have to drop more like 20- 30% below historical rates than have been
typical for sub-regions for 20 or so years.
This requires us to shift thinking, towards fewer, better-fed, bettergrown cows achieving closer to 90% of bodyweight as milksolids, fed more to full
capacity: all year round (including late pregnancy).
In some cases fewer, more capacious cows may not have survived or lasted so well in a higher-stocked system.
This also means moving from a mindset of “no hungry days” to “100% optimally fed days”.
This can still be done with a largely forage-based system. It does, however, require more careful pasture management, especially at peak, and ideally farms with at least 30% of the area mowable, allowing more supplement to be made during peak growth times.
Some farmers in nutrient-constrained catchments have made conscious decisions to retire vulnerable slopes and wetland, and concentrate on the better classes of
land. Many farms in the Rotorua catchment, for example, have dropped their N loss by 15-25% from what they were doing a decade ago.
The sheep and beef sector is harder hit in all of the catchments where there is grandparented nitrogen discharge allowances.
Clearly the dairy sector is a larger user of N fertiliser per hectare than other pastoral sectors, Dairy NZ figures suggest this is about 120-140kg N/ha/year, and on irrigated properties more like 150-250kg. (DBOY data).
There is still a lot more room for more eco-efficient use of nitrogen fertiliser, in response to tightening nutrient limits.
Farmers we studied in the upper Waikato (Broadlands) were using only 60-90kg of N/ha/year, yet still were achieving the top quartile of pasture eaten in the locale (11-
12.5 tonnes drymatter/ha/year). They were using nitrogen fertiliser more strategically, not overgrazing pastures, and increasingly looking to use crops that fix nitrogen
(lucerne) rather than require it.
In comparison, the sheep and beef sector is harder hit in all of the catchments where there is grandparented nitrogen discharge allowances.
Sheep and beef systems have a lot less room to move than dairy in their ability to reduce N, but in some cases still have reduced N losses by 10-20%.
Often they are not as heavily stocked, as this sector has learned over decades that fewer better-fed animals are more profitable anyway, and have had a focus
on eco-efficiencies, as their margins have been tighter.
Their ability to reduce N losses are fewer, they only use around 10-30 kg N/ha (whole farm) typically, little room to move with lower stock rates, reducing or eliminating winter cropping, and in
some cases have to move from a female dominated stock policy to a male dominated policy: from heifers, dairy grazing, to a male (steer/bull) dominated system.
The pressures of nutrient constraints across NZ are starting to slow expansion and intensification. A process of “smart extensification” is emerging.
In some regions like Rotorua Lakes, there is a financial incentive for land use change.
This is not present in all catchments, however. The pressure coming on in all regions to reduce N losses is just the beginning of tightening of a range of limits.
While many farmers have rolled up their sleeves and got on with it in regions that have had rules for a while, others like Waikato and Greater Wellington are just starting to get going.
The issue is not going to go away, farming will adapt, as many good farmers have done already.
Be aware of all your options early, because farm systems take time to adapt and change, especially if you are to get more milk from fewer cows.
