正在经历一场比较严重的类似Flu过程，也许是Covid, 反正quick antigen自测的结果是阳，不发烧不咳嗽，有点头疼，嗓子有些疼但吃东西不影响，胃口好，吃什么都香。主要是嗓子不舒服，说话困难，这两天才有点痰，咳嗽了几次，说话恢复了些，赶紧趁着嗓子不好，录几句留作纪念。
Food comes from farming, entensive and extensive farming has caused severe soil erosion. Humans are facing the greatest of all dilemmas: how to feed ourselves without destroying the living systems on which we depend.
So what can we do? Some pioneered approaches like maintaining soil health during the whole farming cycles, breeding new perennial crop species to replace the annual plants from which we obtain the great majority of our food, provided the promising methods that can reduce soil erosion as in the cases of convensional farming and increase the sustainability of the current living system.
A British farmer’s revolutionary model of horticulture looks like magic, but is the result of years of meticulous experiments
Of course, we would still need to produce cereals, roots, fruit and vegetables. So how do we do it safely and productively? The answer might lie in our new understanding of the soil.
On a farm in south Oxfordshire, techniques developed by a vegetable grower called Iain Tolhurst – Tolly – seem to have anticipated recent discoveries by soil scientists.
Tolly is a big, tough-looking man in his late 60s, with etched and weathered skin, a broad, heavy jaw, long blond hair, one gold earring, hands grained with earth and oil. He started farming without training or instruction, without land or any means to buy it. After a string of misadventures, he managed to lease seven hectares (17.3 acres) of very poor land at a reduced rent, 34 years ago.
“No conventional grower would even look at this ground,” he told me. “It’s 40% stone. They’d call it building rubble. It isn’t even classed as arable: an agronomist would say it’s only good for grass or trees. But over the past 12 months, we harvested 120 tonnes of vegetables and fruit.”
Astonishingly, for these 34 years Tolly has been farming this rubble without pesticides, herbicides, mineral treatments, animal manure or any other kind of fertiliser. He has pioneered a way of growing that he calls “stockfree organic”. This means he uses no livestock or livestock products at any point in the farming cycle, yet he also uses no artificial inputs.
Until he proved the model, this was thought to be a formula for sucking the fertility out of the land. Vegetables in particular are considered hungry crops, which require plenty of extra nutrients to grow. Yet Tolly, while adding none, has raised his yields until they’ve hit the lower bound of what intensive growers achieve with artificial fertilisers on good land: a feat widely considered impossible. Remarkably, the fertility of his soil has climbed steadily.
On my first visit, one June, I was struck by the great range and health of Tolly’s crops. One plot was a blue haze of onion plants, another a patchwork of sea greens: young cauliflower plants, several kinds of cabbage and kale. There were rows of rainbow chard with gold, green, white and crimson stems. Broad bean pods had begun to sprout from tight pillars of flower. His potatoes were in full bloom, nightshade sinister, stamens like yellow stings. Courgettes extruded rudely behind their trumpet flowers. There were carrots, tomatoes, peppers, beans of all kinds, herbs, parsnips, celeriac, cucumbers, lettuces. He raises 100 varieties of vegetables, which he sells in his farm shop and to subscribers to his veg box.
Separating the plots were untended banks, in which scientists studying his farm have found 75 species of wildflowers. These banks are an essential component of his system, harbouring the insect predators that control crop pests. Though he uses no pesticides, none of the vegetable plants I saw showed signs of significant insect damage: the leaves were dark and wide, with scarcely a hole or a spot.
Almost single-handedly, through trial and error, Tolly has developed a new and revolutionary model of horticulture. At first it looks like magic. In reality, it’s the result of many years of meticulous experiments.
Two of his innovations appear to be crucial. The first, as he puts it, is to “make the system watertight”: preventing rain from washing through the soil, taking the nutrients with it. What this means is ensuring the land is almost never left bare. Beneath his vegetables grows an understorey of “green manure”, plants that cover the soil. Under the leaves of his pumpkins, I could see thousands of tiny seedlings: the “weeds” he had deliberately sown. When the crops are harvested, the green manure fills the gap and soon becomes a thicket of colour: blue chicory flowers, crimson clover, yellow melilot and trefoil, mauve Phacelia, pink sainfoin.
“There’s green manure under the green manure,” Tolly told me. “As soon as we cut the bigger plants, it comes into flower, and the bees go crazy.”
Some of the plants in his mix put down deep roots that draw nutrients from the subsoil. Every so often, Tolly runs a mower over them, chopping them into a coarse straw. Earthworms pull this down and incorporate it into the ground. “The idea is to let the plants put back at least as much carbon and minerals as we take out.”
Tolly tells me that “the green manure ties up nutrients, fixes nitrogen, adds carbon and enhances the diversity of the soil. The more plant species you sow, the more bacteria and fungi you encourage. Every plant has its own associations. Roots are the glue that holds and builds the soil biology.”
The other crucial innovation is to scatter over the green manure an average of one millimetre a year of chipped and composted wood, produced from his own trees or delivered by a local tree surgeon. This tiny amendment appears to make a massive difference. In the five years after he started adding woodchip, his yields roughly doubled. As Tolly explains: “It isn’t fertiliser; it’s an inoculant that stimulates microbes. The carbon in the wood encourages the bacteria and fungi that bring the soil back to life.” Tolly believes he’s adding enough carbon to help the microbes build the soil, but not so much that they lock up nitrogen, which is what happens if you give them more than they need.
[A human tongue with each colour representing a different type of microbe.]
Microbes are ‘unknown unknowns’ despite being vital to all life, says study
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What Tolly appears to be doing is strengthening and diversifying the relationships in the rhizosphere – the plant’s external gut. By keeping roots in the soil, raising the number of plant species and adding just the right amount of carbon, he seems to have encouraged bacteria to build their catacombs in his stony ground, improving the soil’s structure and helping his plants to grow.
Tolly’s success forces us to consider what fertility means. It’s not just about the amount of nutrients the soil contains. It’s also a function of whether they’re available to plants at the right moments, and safely immobilised when plants don’t need them. In a healthy soil, crops can regulate their relationships with bacteria in the rhizosphere, ensuring that nutrients are unlocked only when they’re required. In other words, fertility is a property of a functioning ecosystem. Farm science has devoted plenty of attention to soil chemistry. But the more we understand, the more important the biology appears to be.
Can Tolly’s system be replicated? So far the results are inconclusive. But if we can discover how to mediate and enhance the relationship between crop plants and bacteria and fungi in a wide range of soils and climates, it should be possible to raise yields while reducing inputs. Our growing understanding of soil ecology could catalyse a greener revolution.
I believe we could combine this approach with another suite of innovations, by a non-profit organisation in Salina, Kansas, called the Land Institute. It’s seeking to develop perennial grain crops to replace the annual plants from which we obtain the great majority of our food. Annuals are plants that die after a single growing season. Perennials survive from one year to the next.
Large areas dominated by annuals are rare in nature. They tend to colonise ground in the wake of catastrophe: a fire, flood, landslide or volcanic eruption that exposes bare rock or soil. In cultivating annuals, we must keep the land in a catastrophic state. If we grew perennial grain crops, we would be less reliant on smashing living systems apart to produce our food.
For 40 years, the Land Institute has been scouring the world for perennial species that could replace the annuals we grow. Already, working with Fengyi Hu and his team at Yunnan University in China, it has developed a perennial rice with yields that match, and in some cases exceed, those of modern annual breeds. Farmers are queueing up for seed. While annual rice farming can cause devastating erosion, the long roots of the perennial varieties bind and protect the soil. Some perennial rice crops have now been harvested six times without replanting.
Perennials are their own green manures. The longer they grow, the stronger their relationships with microbes that fix nitrogen from the air and release other minerals. One estimate suggests that perennial systems hold five times as much of the water that falls on the ground as annual crops do.
The Land Institute is developing promising lines of perennial wheat, oil crops and other grains. The deep roots and tough structures of perennial plants could help them to withstand climate chaos. The perennial sunflowers the institute is breeding have sailed through two severe droughts, one of which entirely destroyed the annual sunflowers grown alongside them.
While no solution is a panacea, I believe that some of the components of a new global food system – one that is more resilient, more distributed, more diverse and more sustainable – are falling into place. If it happens, it will be built on our new knowledge of the most neglected of major ecosystems: the soil. It could resolve the greatest of all dilemmas: how to feed ourselves without destroying the living systems on which we depend. The future is underground.
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