Ngāi Tahu Farming chief executive Andrew Priest manages more than 100,000 hectares of farm and forestry land in the South Island.

Ngāi Tahu Farming will milk 14,000 dairy cows just north of Christchurch, once the remainder of Eyrewell Forest is felled.

However, the South Island iwi-owned business has abandoned plans to convert some of Balmoral Forest in North Canterbury to dairy, after failing to get the required nutrient and water consents, instead focusing on beef grazing and possibly orchards.

Ngāi Tahu Farming (NTF) manages more than 100,000 hectares of farm and forestry land in the South Island. Its asset value had lifted from $110 million in 2010 to $440m now as properties were developed.

Chief executive Andrew Priest said its 6757ha Te Whenua Hou dairy development, north of the Waimakariri River, would continue as trees were cleared from Eyrewell Forest.

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It had eight dairy farms, six dairy support and six grazing, but planned to expand this to 14 dairy farms and six dairy support, carrying a total of 14,000 cows.

Dairy farming was relatively new for NTF, with investment approved in 2010 and the first farm becoming operational in 2013.

MARJORIE COOK/STUFF Balmoral Forest, near Culverden, was being converted to beef grazing and possibly horticulture, in a longer term development.

"Our oldest dairy farms are only year six, so we are still lifting productivity," Priest told the New Zealand Grain and Seed Trade Association's annual conference in Christchurch. Monitoring using underground lysimeters showed its nitrate loss was less than half its consented amount, he said.

Its 9400ha Balmoral Forest, near Culverden, was being converted to beef grazing and possibly horticulture, in a longer term development. It had 1500ha under centre pivot irrigation and had consents for enough water to extend this to 3000ha.

The development was new, with a pilot farm started in 2016 and beef farms in 2017.

In a trial orchard started this year, it was testing the suitability of four apple varieties, apricots, peaches, almonds, olives and truffle-infused oaks for a potential horticultural venture.

"We know that there has historically been a lot of orchards in that area. Work with Plant and Food Research and Niwa suggests there is potential.

"We have high hopes for this as we certainly have plenty of land," Priest said.

As the business was run under an iwi model, its shareholders had a strong requirement for social and environmental responsibility.

Water quality for mahinga kai (customary food gathering) and other cultural and environmental aspects were vital considerations for tribal members, so the dairy development was being approached cautiously.

NTF's mission statement was: "When land and water are sustained, the people will prosper".

"Everything we do gets a strong litmus test against this philosophy, but it is in the context of farming," Priest said.

LAWRENCE SMITH/STUFF Ngāi Tahu Farming will milk 14,000 dairy cows just north of Christchurch, once the remainder of Eyrewell Forest is felled.

To measure nutrient movement, in particular nitrate, through the soil profile, soil samples from across its Te Whenua Hou development had been placed in 45 44-gallon drums, known as lysimeters, in an underground bunker.

"We now have three years of data. Te Whenua Hou has consents for 60 kilograms a hectare of nitrate loss, but the lysimeters are telling us the actual figure is 28kg a hectare.

"Which is more of an indication of what a blunt instrument Overseer is. I also hope it is something to do with our farming practices," Priest said.

A software modelling tool, Overseer was used by regional councils to calculate each farm's nitrogen loss figure.

NTF was the biggest user of variable-rate irrigation in the world across its farms as well as making extensive use of soil moisture meters, Priest said.

"This means farm managers know not to turn a centre pivot irrigator on as 12mm of rain is expected tomorrow. Trusting the technology is really paying off."

An extensive planting programme of 60,000 mainly native trees was being planted in reserve areas and around pivots at Te Whenua Hou.

"So there is a significant amount of restoration work going on."

NTF had vowed to cut its greenhouse gas emissions 29 per cent by 2030, with electric tractors and solar panels some of the ways it would meet its obligations.

Previously under Ngāi Tahu's property portfolio, farming became a standalone business in 2015, sitting alongside capital, property, seafood and tourism.

NTF also manages three high country stations, Routeburn, Greenstone and Elfin Bay, totalling 35,500ha near the head of Lake Wakatipu, as well as 49,000ha of West Coast forest (formerly Timberlands).