Peat Lake Post-Restoration

August 2013

A visit to a Waikato farmer with a lake restoration programme underway

Peat lake restoration work began for the Hayes family at Horsham Downs near Hamilton in 1999 with willow removal around the 16ha Lake Kaituna, which is fully enclosed within their 88ha effective dairy farm. Fencing out stock, riparian planting, silt trap construction and then a Whole Farm Management and Environment Plan followed. The herd remains within the top 5% of production for Waikato, now farmed adjacent to a rescued lake teeming with waterfowl and fish, surrounded by self-regenerated native plants. The farm is also in the bottom 10% for nutrient loss.

Over 20 years Andrew and Jenny Hayes and their four sons Alastair, Derek, Rodney and Fred have worked towards rescuing the health of two lakes on their dairy farm, called Lakes Kaituna and Komakorau, from excessive nitrification and the death of fish, birds and vegetation. Dense willows around the lake supressed all other growth and self-seeded, as well as dropping leaves to foul the lake. They cleared willows around the lake edge with about one thousand hours of chainsaw work, then spraying with diesel and Roundup, followed by digger collection of timber and bonfires. What was conceived as a 10-year plan was completed in seven years. They retired a 10m by 3km strip around the lakes for wetland regeneration and restoration, which amazingly filled with self-regenerated native trees, rushes and reeds. With the willows gone, the natives that had been suppressed underneath came away and there is a vigorous riparian margin of cabbage trees, kahikatea, kowhai and manuka, along with carex, sedges and reeds, which have established naturally. A little planting of kahikatea has been done to help them along.

None of the farm’s drains now discharge directly into the lake, but go through silt traps and then percolate through the wetland fringes of the lake. An access track was made around the reserve’s outer ring and in a few places into the wetland to allow access for weed control and planting. The family identifies any sizeable native plants they find with stakes so they don’t get sprayed with weedkiller, and pot up small seedlings, which they return to the reserve when grown. The lake is covered with water fowl that don’t stray on to the farm because there is so much food for them in the restored habitat. “When we came here the ducks were in the water troughs and the cows were in the lake,” Jenny has said. Now waterfowl and livestock are in their right places. Among the bird life are ducks, shags, pukeko, bitterns, geese, swans, fantails, spotless crakes, pied stilts, royal spoonbills and egrets.

There is a problem with koi carp and gambusi, both pest fish, but efforts are underway to remove them, and native mudfish are being released by University of Waikato to restore a more balanced ecosystem.

The cost of fencing, a little planting and weed spraying which was $9,000 a year during the establishment phase, was met a third each by the farm, Environment Waikato through its Clean Streams funding, and the Department of Conservation, and the ongoing spray programme for weeds and willow regrowth is now costing $1,000 pa. About 4km of riparian fencing has been done and 5ha retired from grazing, although the farm stocking rate has been kept around 300 cows.

Lake Kaituna (also known as Lake B) is one of eight small peat lakes in the Horsham Downs district. Kaituna is hydrologically linked to the smaller Lake Komakorau, both located in an agricultural catchment once part of the now drained Kainui peat bog. Both are part of a chain of 38 Waikato peat lakes that are remnants of a once great, 60,000ha wetland. A cluster of eight lakes at Horsham Downs vary in size from 6ha to 33ha. These lakes are silting up and in varying states of eutrophication from excess sediments and nutrients running off from surrounding farms. Andrew says Lake Kaituna shrank from 3-4m depth to one metre over the 30 years he has owned the farm.

The Hayes run 290 Kiwi-cross cows on 88ha effective which is a high stocking rate of 3.4cows/ha. They are now share-milked by youngest son Fred. They are among the top 5% of Waikato herds in milk solids production per hectare and per cow while using only a third of the average rate of nitrogen fertiliser. The farm is also among the lowest 10% of Waikato farms in nutrient loss. Drought tolerance has also been improved. The slower release of water into the lake means the pastures uphill dry out more slowly in the summer, and the silt captured from the traps and spread on the farm returns a number of minerals that improve fertility. Loss of peat and fall in soil profile is minimised by keeping soils wetter during summer. Production was 133,000kg milk solids in the 2011-12 season and 113,000kg in the 2012-13 drought-affected season.

Big changes have been made to the fertiliser use and nutrient management on Lakelands Farms. Andrew says applied fertiliser has been cut to what the pasture requires so as not to cause run-off into the lakes. Applications are now made in liquid and slurry, using products from Outgrow and Clovertone. Nitrogen inputs have reduced gradually from 180 kg/ha N to just 24 kg/ha N by using a low rate of sulphate of ammonia. Effluent is irrigated over 90% of farm with travelling irrigator at 12ml/pass, applying N16, P5 and K20. System takes one year to cover whole farm. No potassium fertiliser applied since 2004, no phosphate applied last three years. N loss is now down by 35% since 2004 to 25kg/ha/yr. N use efficieny has risen 40% over the past decade. P loss has fallen to 2.5kg/ha/yr from 3kg a decade ago.

Clovertone is being applied to half of the farm. It consists of plant extracts, boron, cobalt, copper, iron, magnesium, manganese, molybdenum, nitrogen, selenium, sulphur and zinc. It also contains other nutrients which feed the soil bio-mass. It has no phosphate or potash. Outgro Vegetative Foliar and Soil Revitaliser consists of humic acid, fulvic acid, all trace elements and minerals.

The Hayes lead the Kaituna/Komakorau Lake Care Group of family, friends, neighbours and supporters. Some of the work the group has done so far has included fencing, planting, designing and installing silt traps, applying the Whole Farm Planning process, installing floating wetlands and pest and weed control. The Hayes also open the area to the public including schools and a variety of other users all interested in the unique and diverse ecosystems these lakes support.

Local landowners, DOC, Waikato Regional Council, NZ Landcare Trust, University of Waikato, DairyNZ, duck shooters, and conservation volunteers are all on board.

In 2007, the Hayes family were recognised for their outstanding work by the Ministry for the Environment with a Green Ribbon Award for Rural Sustainability. In 2012 they were awarded one of the inaugural Landcare Ambassador Awards presented by the Minister for the Environment. It was said at that presentation: “It’s Andrew’s willingness to share his experiences about farming in a sensitive lake catchment that really adds another dimension, with a variety of events regularly taking place on the farm and lake shores.”

Andrew and Jenny have been documenting their farm’s financial and management progress over the past five years, and sharing it with other farmers that are keen to learn how to farm in a profitable, but lower impact manner.

DOC Biodiversity programme manager John Gumbley spends about three-quarters of his time on Waikato peat lakes and wetlands restoration, prioritising fencing, planting and installing pest fish barriers. Pest fishes like Koi carp are contributing to the nutrient enrishment of the lake waters and contributing to the degradation. He has input to farm environment plans to introduce more sustainable management practices and increase farm profitability, which might be changes in fertiliser use or standing pads.

Preserving the peat lakes and wetlands also helps in minimising peat loss, which around Waikato and Hauraki Plains can be 3cm/year through drying out and erosion. What has been achieved by the Hayes and their helpers for Lake Kaituna in 15 years is quite remarkable, says Gumbley, because normally 100 years of degredation cannot be turned around quickly. “This lake provides a recipe to demonstrate how other lakes and wetlands can be improved,” he said. Kaituna is also home to a constructed floating wetland about 30m square, containing plants, and its effectiveness is being monitored by DOC.

In terms of increased biodiversity, the lake now contains short-finned eels, bullies, inanga, giant kokopu and black mudfish, as well as the pest species. John can also point out the variety of native plants which have established spontaneously in the riparian margin.

DOC’s objectives for the $20 million Living Water partnership were announced recently by Fonterra. Director General Al Morrison said DOC quality waterways are pivotal to maintaining the healthy environments which protect native wildlife and also underpin a sustainable dairy industry.

“We all realise that our waterways need ongoing support and it makes perfect sense for DOC to be working with New Zealand’s largest dairy co-operative to improve water catchment health. By working together, we can deliver additional conservation gains in some of our most sensitive catchments.”

As the expert in conservation and biodiversity, DOC will work with Fonterra, local communities, iwi and farmers to help clean up waterways and wetlands at the five selected catchment areas. This will include planting trees alongside streams and rivers to improve water quality, managing pests and weeds and making sure that the right habitats are in place around farms to enhance biodiversity and provide homes for native fish and birds.