From muck to money

A dying lake is a grim sight. It also stinks, as the Hayes family will tell you. In the summer of 1998-1999, a skin of green slime 25cm deep covered the two lakes bordered by their dairy farm in Horsham Downs, north of Hamilton. The stench from the rotting fish and birds in the putrid water was like silage, recalls Andrew Hayes (pictured). “We knew from the stink there was too much nitrate going in.”

Lake Kaituna, fully encircled by the 90ha farm, and its little sister a stone’s throw away, Lake Komakorau, were dead; best predictions were that within 25 and five years respectively they’d be swamps.

But the Hayes weren’t about to let that happen. Taking what they’d learned from working on another sick lake opposite their property, they set about saving their waterways.

Thirteen years on, the lakes thrum with bitterns and fernbirds, spotless crakes and oyster catchers, pied stilts and ducks. A rare white heron even winged in this spring. Native plants form a wetland buffer zone around both, absorbing some of the nutrients from the much-reduced farm runoff. Nitrate and phosphate levels in the water have dropped right back. (These nutrients fuel the excessive growth of aquatic plants that eventually choke rivers and lakes.) And the Hayes’ farm is in better shape – environmentally and financially – than it’s ever been.

The plan of attack

So how do you revive a dead lake and improve your business?

First, you rally the troops. The Hayes formed a care group with the Department of Conservation, Waikato Regional Council, duck-shooters and friends. The group set goals and divvied up tasks. Andrew Hayes and his four adult sons started clearing the self-seeding willows that were encroaching on both lakes, “so thick a bloody rabbit couldn’t get into them”.

Sedimentation was a huge problem; the willows were suppressing other plant life, their leaves fouling the water. But the lake’s biggest enemy was the farm run-off which drained straight off the farm, underneath the willows into the lake (unlike natives, willows absorb few nutrients in winter, when rainfall is the heaviest). There was no quick fix; but there was a fix. Over the next seven summers, the Hayes, helped occasionally by volunteers, cleared 16ha of willows and other invasive plants. It took more than 1000 chainsaw hours – all unpaid – and cost $7000-$9000 per year, a third each from the Hayes, DoC and the council.

Says Andrew, “People said we were mad but we did it, and everybody else does it now. DoC thought it couldn’t be done, because of the scale of it, they were shocked.”

They dug out silt traps along drains, small ponds in which silt settles. They fenced the lake and all the drains so cows could no longer directly foul the water (DoC and the Hayes split costs). To create the riparian strip – the thirsty natural buffer – the Hayes retired a 10m by 3km strip of land bordering the lakes for wetland regeneration and restoration, planting it with native trees, rushes and reeds. Fonterra-sponsored volunteers helped the Hayes with the planting; the trees were paid for by DoC and the Honda Tree Fund, and supplemented by seedlings from the Hayes’ own nursery. And Andrew’s got his investment back: thanks to the soil moisture-balancing effects of the wetlands, the farm does better through dry spells.

The next step was to reduce the nutrients the Hayes were putting into the ground and waterways. DoC paid for consultant Alison Dewes of Headlands to run an in-depth audit of the farm’s business and environmental performance and generate a plan for the farm to maximise profits while minimising the eco-footprint. Three years on, the soil and cows are healthier, fertiliser bills are down and productivity is up.

Andrew: “We’ve cut the fertiliser down to what the grass requires; before it was running into the lake.” He’s also switched from solid to liquid and slurry fertiliser by Outgrow and Clovertone, two small New Zealand companies.

Waikato University, Landcare and DairyNZ are all now involved in the ongoing care and monitoring of the lakes.

A smarter future

Eventually, nutrient reduction will be standard practise, Andrew maintains. “It’s gotta come, there’s too much nitrate going down to the river or lake. What they’re measuring in the waterways, someone’s paid for that to farm with. It’s money going down the drain.”

Today, the Hayes have a spectacular view of the lakes from their window, a view once blocked by willows. When they bought the farm in 1981, it was rundown. They started with 44ha and 100 cows, building up to the current 90ha (88 effective) and 300 cows.

Andrew insists he’s no green crusader. “I’m not a greenie; it’s just practical, common sense. We can’t have our waterways with signs up saying ‘you can’t swim here’. Where a lot of farmers have gone wrong is they’ve lost touch with the processes of recycling, lost an understanding of how to use their natural resources; how to work with them not against them.”

The numbers

• Milk solids: 1500kg/ha (up from 1200 in 2004/5, industry average 978kg/ha)
• Milk solids per cow: 440kg (up from 353 in 2004/5, industry average 310kg)
• Return on total assets: 9 per cent at a $7.50 milk price (industry average around 5 per cent)
• Nitrogen leached: 28kg nitrogen per ha per year (down from 38 in 2004/5, regional average around 35kg)

Greener pastures

Following a business and environmental audit of the farm:

• The fertiliser bill has been cut by 25-30 per cent
• Root depth is 218mm
• Worm count per spade jumped from 10 to 21
• Clover – an indicator of healthy soil – is up 800 per cent just on last year
• Stock losses from afflictions connected to nutrient deficits, such as grass staggers and milk fever are near nil
• The “empty rate” (cows that don’t produce calves) has dropped from 10-15 per cent to 2 per cent of the herd

Saving two lakes needed...

• About $60,000, seven summers and more than 1000 chainsaw hours to clear 16ha of willow trees and other invasive plants
• 4km of fencing around lakes
• 5ha of farmland retired for natural regeneration and replanting of wetland vegetation (however, stocking rates held steady around 300 cows)
• Silt traps on 21 drains, to catch sediment before it enters the lakes

Useful links

www.biologicalfarmers.co.nz
www.integritysoils.co.nz
www.overseer.org.nz
www.dairynz.co.nz/irrigation

Future farms

Developments in smart agriculture.

Just enough food

Nutrient budgeting and management take the guesswork out of fertiliser use, minimising accidental overuse, which saves money and reduces the amount of nitrogen and phosphorous that ends up in waterways. Free software called Overseer creates a computer model of a farm, accounting for all nutrients and effluence. Soil testing provides a check.

Dairy farmers with 250-300 cows have cut $5000-$10,000 from their annual fertiliser bill with this method.

Moisture monitors

It’s not unusual for farmers to rely on the look of their pasture to decide how much irrigation is needed, which can result in overwatering. This leaves no buffer of absorbency when it rains, increasing nutrient run-off. Some farmers are investing in soil moisture monitors, which enable them to apply the right amount of water at the right time. Instruments cost between $1800 and $4000, but can lead to long-term savings on water charges (where applicable), pumping costs, and prevent flooded pastures. Industry group DairyNZ is working on cheap DIY methods.

Tender tillage

Direct drilling is a way of planting crops that’s often cheaper than conventional ploughing, needing only one pass of the tractor rather than repeated passes, and is more effective. Blades cuts a slit in the pasture just deep enough for seeds which are precision-planted into the cut. It doesn’t disturb the soil as much as regular ploughing, which means less carbon is released into the atmosphere, more worms survive, more organic matter is left intact and more moisture conserved, all of which reduces run-off and makes for richer, healthier soil.

Science, naturally

Also known as sustainable farming, eco-agriculture, or nature farming, biological farming harnesses natural processes and modern science to build health and resilience back into agriculture, with a focus on soil and animal health. Instead of artificial fertilisers a biological farmer might use animal manure or cover crops such as the natural fumigator mustard, which are dug into the ground to enrich the soil. Or they might grow 'predator strips' of plants that attract beneficial insects, such as parasitic wasps. Proponents say they spend less money on fertilisers and pesticides.

Current research

A joint Kiwi-German project is developing a moisture sensor that uses microwaves and dielectrics to measure soil moisture under pasture while mounted on a moving vehicle.

Meanwhile, New Zealand’s Cawthron Institute is investigating DNA analysis of microscopic single-cell organisms called foraminifera from sediment samples. Foraminifera are like the canaries in the mine of aquatic ecosystems, offering insights on water pollution.