Forgotten Corners Lowlands Wines

Forgotten Corners

Down the pathway of regenerative viticulture

SOPHIE PREECE

Robert Holdaway

ROBERT HOLDAWAY sees science at work when he harvests a salad for dinner, plucking rocket, spinach and beetroot leaves from his Lower Wairau Vineyards. He sees a burgeoning above and below-ground biological community when diverse cover crops flourish down the grape rows, flower heads blazing above the green. And he sees a healthy ecology when driving a mule down a vineyard row becomes a “hazardous” occupation, with the bonnet splattered with insect diversity, from aphids to ladybird larvae.

Measuring an ecosystem via tasty salads, pretty flowers and hit-and-run insects seems imprecise. But Robert - who has a PhD in forest ecology from Cambridge University and spent eight years as an ecosystem ecologist at Manaaki Whenua Landcare Research – says such biodiversity is about making the vineyard “hum”, or function properly. “It’s about getting biodiversity back into the vineyard – plants, insects, fungi, bacteria,” he says. “And if you can get the plants feeding the soil life, the soil life will feed the plants and help protect them from disease… you get functional complementarity.” Each plant supports a different niche of insects and micro-organisms, “and you get the predatorprey relationship, and all that balancing that nature does”.

Robert describes himself as an ideas guy, having returned to Lowlands Wines three years ago, when he became disillusioned by the lack of transfer from science to action. “The pure science was out there telling you what to do and it supports the idea that plant diversity and biologically active soil are critical for plant health and ecosystem function.” So he joined his brother Richard, who had finished his engineering degree in 2003 and returned to Marlborough to help expand and develop the family business. If Robert is the ideas, then Richard is the engine. He says regenerative agriculture is easy to say and hard to do, but he was already heading in that direction when Robert returned. Now, they use Robert’s science and Richard’s nous to plant abundantly diverse cover crops, feed the soil biology, implement biological spray programmes, and cut fungicides and herbicide use, in order to seek that utopian “hum”.

Next season, Lowlands Wines is not planning to use any insecticides at all. “Our cover crops mean we hopefully have enough beneficials present, and there are biological controls we can turn to if needed,” says Robert. The brothers are also trying to cut back on fungicides, so in the last growing season ran a trial with no chemical canopy sprays beyond an early-season oil, using a biological programme instead. That meant no fungicides - organic or chemical - no sulphur and no copper, “in an attempt to pull out all the inputs that are killing the good biology”, says Robert.

In the end a touch of powdery mildew led to a single fungicide application across most of the trial block, then a return to the biological programme. “That’s one instead of 14,” says Robert. “We were able to do that because we are not organic. So instead of going in with soaps and sulphurs and nuking it, we were able to do one targeted powdery spray, which we thought was better for the overall ecosystem.”

The results were compelling, and next season half of Lowland’s 155 hectares of Sauvignon Blanc vineyards will be included in the biological trial, “with the caveat that we will monitor the heck out of it, and if we do get some we will do that one fungicide”, says Robert.

He and Richard are adamant that the flexible use of inputs is a key advantage of regenerative viticulture. In the past, companies have been either organic or conventional, says Richard. “We are going the third way.” That’s why it shouldn’t be certified, he adds. “The whole point is that the toolbox is wide open, and holistic management means you use whatever tools you need to do the best thing for the whole”.

When people ask Robert to explain regenerative viticulture, he calls it a mentality, not a set of practices. Decision making becomes about putting the biology and the ecosystem first, because “if we get that thriving, the rest will follow”. That means not asking “how do I kill this problem organism?” but “how can I enhance the environment so that

the pest or disease is naturally supressed?”

Fungi and bacteria play a key role in a plant’s health and defence systems, so killing off everything with a fungicide is “the last thing you want to do”, he says. “In ecology, when you have a slate that is clean, the thing that comes back first is the disease. You see this with the use of harsh chemical controls for mealy bug, for example”. Robert is quick to point out that there is no silver bullet solution - they are still using fungicides. But they use them reluctantly, while continuing to work as hard as they can to improve vine health.

Richard is moving from mitigating herbicide rounds with a biological buffer, to feeding the soil directly all year round with cocktails of biological stimulants to boost the soil’s microbial activity. As soon as harvest ends, they start feeding the bugs for the next season, he says. “It’s your one window in vineyards where you are not driving a tractor through and not putting fungicides on.”

The Holdaway brothers are bemused to see growers doing a winter herbicide spray, or mowing vineyards to a bowling-green neatness. They prefer to let the undervine vegetation grow over winter, feeding both the soil and the sheep while the grapes are dormant. “This is the tidiest you’ll ever see it,” says Robert in August, once the sheep are gone and the fresh green shoots of self-seeded species, including oats, phacelia, mustard and rocket, are pushing up along the row. In summer they let everything grow, mowing occasionally or roller crimping to manage excessive biomass or create undervine mulch.

Land in the Lower Wairau is a “big horsepower system”, says Richard, noting that six trims a season is typical when you “ride the vigour wave”. That means they’ve less to gain from the regenerative viticulture than a grower on less healthy soils. “But there are a lot of other benefits, and disease resistance is the big one,” Robert says. “That is the pot of gold at the end of the rainbow.”

It’s likely to be 10 years before they can “get out of the way” of nature, says Richard. “But we are working really hard to get all the building blocks in place.”

Cranking up the compost Making good compost requires an understanding of techniques for success. The latest blog post from Nelson compost company Wholesale Landscapes outlines the technical aspects and processes of making compost, including the goals of breaking down organic materials while destroying plant disease organisms and biological pathogens through the natural heat created through decomposition. That process needs to be done in the shortest possible timeframe, because compost loses carbon and nitrogen to the air as it continues to heat, the blog explains.

The amount of heat produced in compost is influenced by the speed of microbial metabolism and the dimensions of the compost heap, with larger, higher heaps of compost able to accumulate more heat, they explain. The speed of microbial metabolism is also influenced by the carbon to nitrogen (C:N) ratio, and the moisture content of the mixture. “The C:N ratio is used to predict the effect that the compost is likely to have on plant available nitrogen in the soil and as an indicator of the rate of decomposition. A C:N ratio of about 30 is considered nitrogen neutral - lower ratios will release nitrogen and act as nitrogen fertilisers and higher ratios will immobilise nitrogen as microbial breakdown of the carbon component occurs. In the long term, the nitrogen content will become ‘available’ as carbon decomposition occurs.”

The Wholesale Landscapes piece notes that a bad ‘sour’ smell indicates inadequate decomposition or lack of air, which causes anaerobic microbial activity. “This is typical of a pile of grass clippings left to ‘rot’ where there is no air in the centre of such a pile, the centre is generally dull green, gooey and stinks.”

Commercially made compost provides approximately a year of nutrients into the soil, they say. “The amount of nutrients and value that brings to the soil is determined by the compost inputs. A high quality compost will have beneficial nutrients past one year, however, this is generally when they start diminishing.”

The blog, which was written in collaboration with John Turner of Hill Laboratories, is available at wholesalelandscapes.co.nz/Tips-Advice-Articles

Yealands Estate