Karen Trebilcock

The focus was on good management practices at a DairyNZ field day in North Otago in mid-April which looked at ways to farm below the nitrogen limits set by Otago Regional Council (ORC).

With few rules or requirements for consents to dairy in the region, ORC is relying on farmers to complete Overseer nutrient budgets to make sure they are farming under, for most of the province, 30kg N losses per hectare per year from April next year.

DairyNZ Otago catchment engagement leader Hanna Stalker said there were many things farmers could do to farm under the limits without having to spend money on capital infrastructure.

“Good management practices are the key as well as documenting what you are doing. The more information you have about what you are doing on your farm the better,” she said.

“Make sure you document everything so all of the information going into Overseer is as accurate as possible.

“If you are creeping up to that 30 figure then first of all look at the DairyNZ good management practices (available on the website) and see what you can implement on your farm.

“We’re not telling you how to farm, you know your farm better than we do, but following these practices will get your nitrogen leaching figure down on your farm.”

Fonterra suppliers must already complete Farm Environment Plans (FEP) and she said it was important to complete predictive plans at the start of each season and to have another look at them at the end of the season to see the final N figure.

“See how what you are doing is changing your figure. Know what makes a difference.

“Simple things like getting culls away early and knowing the date and how many went when to put into Overseer correctly can make a huge difference.”

The mid-April field day was held at Phil and Becky Wilson’s farm near Ngapara in North Otago which has a challenging topography with limestone outcrops, steep faces and the Alps 2 Ocean Cycle Trail running along one of its boundaries.

The soils are mainly Pallic and it straddles two catchment areas – the Awamoko and the Waiareka and also has multiple natural springs.

They milk 840 crossbred cows on 216 hectares effective supplementing with fodder beet in the shoulders, palm kernel and barley in the dairy. Wintering is off farm.

Catch crops such as oats are grown after the fodder beet.

Their N loss figure for the 2017/2018 season is 26.

Phil said areas of the farm had been retired in the past few years – fenced off and left in rank grass.

“I was worried someone would roll the four-wheeler on some of the steep slopes so it made sense from a health and safety point of view, but also environmentally, to stop farming them.

“We weren’t getting much production off them anyway.”

At the bottom of one of the slopes he has also built a pond as a sediment trap to catch nutrients running off the hills and planted it with natives such as kanuka, flaxes and silver tussocks which are endemic to the area.

He said using native plants from the area, with seed sourced locally, made sure the plants were able to tolerate the area’s dry summers and frosty winters.

Other ways nitrogen leaching has been reduced onfarm is by applying urea from August to April only if the weather allows. Soil testing has shown P levels are above optimum.

The fertiliser spreader onfarm is regularly serviced to make sure it is self-calibrating correctly.

Effluent applications, which are through the farm’s pivot and through a travelling irrigator on 82ha, are recorded in the dairy diary along with staff training records. An effluent WOF has been done.

The storage pond is clay-lined and a drop test is on the to-do list.

“Even though ORC don’t have rules about how much storage you should have that doesn’t mean you shouldn’t carry out good management practices,” Hanna said.

“Use the dairy effluent storage calculator which uses rainfall and the number of cows to work out how much storage you need and knowing where you are spreading your effluent and treating it as a nutrient source, along with your fertiliser, makes good sense economically and environmentally.

“Do the bucket test to see how much your spreader is putting out. DairyNZ has buckets you can use at all Farm Source stores and there is a free app you can download to do the calculations.”

The farm receives 124kg N/ha/year from effluent.

Farm lanes are well away from waterways with paddocks acting as buffers. Troughs and supplement feed are also placed away from the waterways.

All waterways are fenced with wide riparian margins.

Irrigation water is from NOIC (North Otago Irrigation Company) and is only used when portable probes and Aquaflex tape show soil water deficits.

Three centre pivots cover 163ha with K-lines, which are shifted twice daily, covering 54ha.

All water takes are monitored and the cooling water at the dairy is recycled and the yard wash is with green water.

Annual servicing of the pivots is carried out by Waterforce and bucket tests, to check accuracy, are also done once a year.

DairyNZ Canterbury catchment engagement leader Katherine McCusker said farmers should use a spade to know what moisture levels looked like in their soil structure.

“It is really important to use probes but make sure you know what those figures look like in the soil,” she said.

Putting the right amount of water on at the right time grew more grass but too much flooded the areas below the root zone and flushed nitrogen through the soils.

“Make sure the water is where you want it. One of the biggest drivers in Overseer

is how much water you are irrigating so you need to know how much is going on and where.”