Innovative growers are starting to think small in New Zealand – with some impressive results. Anthony Byrt goes down on the farm with bio-intensive market gardener Jodi Roebuck.
Innovative market gardeners are starting to think small in New Zealand – with some impressive results.
Along a wooden bench under a transparent plastic roof, trays and trays of tiny plants grow in incredible colours: autumnal reds, trippy purples, and multiple depths of green – a miniature forest of peas and amaranth and mustards. It’s pretty as hell. Tobi, a tall, archetypally German 21-year-old travelling the world to learn about biointensive gardening, explains how the microgreens set-up works.
The crop grows in a matter of days, he tells me, and a 70g bag goes for $5. The morning’s quick 800g harvest, then, has yielded about 60 bucks. Then he breaks up a chunk of tray soil and holds it up to me. Thick with roots, it’s perfect, carbon-rich material for composting. Next to the microgreens, tightly packed tomato plants reach for the roof, covered in fruit. Just behind them are cucumbers, climbing up wires. Every space of the makeshift greenhouse is growing something. Tobi’s boss, Taranaki market gardener Jodi Roebuck, can’t remember the German name for the tomatoes. “Riesentraube,” Tobi intones, perfectly.
Roebuck, who’s based just outside New Plymouth, made his name as a restorative grazier, taking land where the soil and pasture had been hammered by overgrazing – including the 2.8ha block he and his wife bought in 2004, but mostly other people’s – and turning it into rich, fertile, bio-diverse pasture. By “mob grazing” his sheep intensively in small spaces, for a matter of hours or a day at most before moving them on, he slowly transformed the landscape, and the soil quality.
religiously on their farms to get carbon into the ground quickly: tarping. At any given time in Roebuck’s garden, a solid number of his beds are under black tarps. Usually, this is after he’s grown some kind of cover crop. As the cover crop grows, it helps to put nutrients like nitrogen and carbon back into the soil through root exudates. In the winter, Roebuck’s preferred cover crop is oats; in summer, it’s buckwheat.
When those crops get to a reasonable level of maturity, Roebuck chops and drops them in place, then covers the whole bed with a tarp. Without light and with the extra heat generated under the cover, the plant material starts to decompose quickly. Worms come up to harvest it and take it back down. The result is a huge injection of carbon in a short timeframe. After a few weeks – instead of the months tied up in conventional composting – and with a bit of added manure, the bed is ready for the next vegetable crop.
In a recent conversation, Roebuck tells me about a new cover-crop technique he’s using: growing microgreens in outdoor beds rather than a greenhouse. Twice a week, he sows peas in 3m strips that take 12-14 days to reach microgreen maturity. In that time, 25% of the plant’s energy is given off through root exudates, feeding the soil, while the roots themselves develop into that carbon-rich humus Tobi had so proudly showed me in the greenhouse.
“It’s basically a two-week cover crop,” Roebuck says, excitedly. “We make 750 bucks off a bed, we tarp it, and three to five weeks later we’ve got this bed of gold we can then plant back in.”
There’s a big reason these guys spend so much time thinking about carbon and tinkering with soil structure: it’s the crucial ingredient in the quality of their product, its marketability, and their eventual profitability. Carbon-rich soil results in stronger plants and nutrientdense produce, which is healthier and tastier for consumers. Healthier plants also have much better insect resistance. The depth of the soil matters too, which is why having permanent beds, rather than whole fields that are ploughed between harvests, is so important. Exposing soils releases soil carbon; the longer they’re uncovered, the more carbon is lost. But permanent beds can be deepened and enriched, while being almost constantly covered.
Both Roebuck and Fortier swear by the broadfork as the essential tool for this, its long tines aerating soil and working in organic matter without actually turning the bed over. Deeper soil means plant roots can grow down rather than across. As a result, they aren’t competing with each other for nutrients, and more can grow in a smaller space. And when the plants mature, they cover the entire bed, reducing weed pressure and eliminating the need for glyphosate.
There’s a bigger-picture point about this focus on soil carbon, too. At the 2015 United Nations Climate Change Conference in Paris, which led to the Paris Agreement, France introduced the “4 per 1000” initiative. Essentially, this was a proposal that all nations increase their soil-carbon stocks by 0.4% per year. The key to this is more intensive planting – grasslands, pasture, forestry, and food crops – not only because the plants themselves absorb carbon dioxide from the atmosphere while they’re growing, but because the organic matter they generate
“I don’t believe small farms can feed the world,” Stone tells me. “I’m more of a pragmatist than a lot of people in this space.”
can be used to sequester carbon in soils. And that improves soil quality, helping to address one of climate change’s great existential threats: food security.
Roebuck is a huge believer in the potential of soil-carbon sequestration and its effects on healthy food production – it’s a key factor in both his gardening techniques and his sheep grazing. “I know farmers that are farming 5000 acres [2020 hectares] and sequestering carbon, with maybe one employee,” he says. “That’s effective. Whereas if we look at feed lots and hard ‘grazing’, if we can even call it that, it doesn’t look too good for the planet.”
From an ecological perspective, then, there’s a lot to commend the new biointensive market garden, which prioritises soil carbon, cover cropping, space and water efficiency, and nutrient density. In New Zealand, it could also start to answer one of our major challenges. Population pressure is making land seriously expensive. Farms, orchards and market gardens are being chopped up and sold in ever-smaller blocks, and often aren’t used for food production after they change hands. This is a threat in areas with some of our most valuable foodproducing soils, such as Pukekohe. Building over that soil is a travesty. If it does happen, at least the bio-intensive model could partly offset the production loss.
However, even its most innovative practitioners are wary of being overzealous. “I don’t believe small farms can feed the world,” Stone tells me. “I’m more of a pragmatist than a lot of people in this space. I think large farms will feed the world. But we can take the things
Roebuck harvests quickly and gets multiple cuts from his intensive lettuce beds. Efficiency is a crucial aspect of his business model.