If the UK switched to a plant-based diet – and used regenerative farming to produce food on the arable land we have (not using artificial fertilisers or pesticides) – how much could we be self-sufficient in food, percentage-wise? dad_climate The calculations that partly address it have been done by the author and small-scale dairy farmer Simon Fairlie, updating the earlier work of the ecologist Kenneth Mellanby. We currently use 17.5m hectares of farmland in the UK. Fairlie finds that while a diet containing a moderate amount (less than we currently consume) of meat, dairy and eggs would require the use of 11m hectares of land (4m of which would be arable), a vegan diet would demand a total of just 3m. Not only do humans need no pasture, but we use grains and pulses more efficiently when we eat them ourselves. This would enable more than 14m hectares of the land now used for farming to be set aside for nature. Alternatively, on a vegan planet, Britain could feed 200 million people. In terms of having a “livestock-free world”, how do you account for the importance of cattle dung and the need for that as a fertiliser for soil? Without livestock, wouldn’t this just create a greater need for harsh chemicals? emmab45 While animal manure might return carbon to the soil, in other respects, contrary to the claims of some practitioners, it is not a great soil additive. One paper reports that the leakage of nitrogen from organic farms using animal manure is 37% worse than the leakage from conventional farming using artificial fertiliser. The problem is timing. While artificial fertiliser often releases its nutrients too quickly, manure releases its nutrients too slowly. If the crop is not to starve, the dung needs to be spread long before the maximum growth spurt. Even then, the plants are unlikely to receive all the nutrients they need to reach their full potential. Nitrogen from manure leaks both before and after crops are able to mop it up. Those who use animal manure argue that the way they farm is how nature works: animals excrete on the ground, plants suck it up, and the cycle sustains itself. But there are few natural systems that look anything like agricultural ones. The vast herds of wild herbivores Europeans encountered when they first arrived in Africa and the Americas are likely to have been an artefact of the suppression of predators by the people who already lived there. Palaeontological evidence suggests that, before humans began competing with them and killing them, large carnivores existed in far greater concentrations than they do in any ecosystem today. Rarely, if ever, would dung have been deposited at agricultural rates. I’m not saying that the use of artificial fertilisers is OK – I’m saying that both sources, in environmental terms, are highly problematic. Our aim should be to minimise the use of all forms of fertilisation, while maintaining high yields. That’s the fundamental challenge some growers are seeking to address. It’s not easy, and a great deal of further work is required before we get there. It may be the only way to live sustainably is to live close to nature in small hunter-gatherer groups, as we once did in the pre-Neolithic. If all you use are wood, bone and stone tools, then there is no waste or pollution? If you are not ploughing fields then there is no habitat destruction? Over-gathering or over-hunting could cause damage, but surely not on the scale made possible by agriculture? robs243 Hunting and gathering would support a really tiny fraction of today’s population. An analysis by Yadvinder Malhi suggests that between 10 and 50 sq km of land is needed to support one hunter-gatherer, while 10 sq km of modern, productive farming can feed 4,000 people. Another estimate suggests that the maximum population of Britain before the Neolithic, when there was no agriculture here, was 5,000. Yes, just 5,000 people. Even so, we managed to destroy populations of many of our large mammals. There was one false statement in this great article – that we have enough food to feed everyone on Earth. That is not true. We have 8 billion people on Earth, growing towards 10 billion people. Dellflorida Global food production has been comfortably beating population growth for 60 years. In 1961, there were 2,200 kcals a day available for every person on Earth. By 2011, this had risen to almost 2,900. Crop production as a whole has risen much higher: to an astonishing total of 5,400 kcal per person per day. But almost half these calories are lost, mainly through feeding the food to farm animals, but also through using it for other purposes (such as biofuels) and through waste. Even so, in principle, there is more than enough for everyone, if it were affordable and well distributed. So how come chronic hunger has been rising globally since 2015? It’s the result of a lethal combination of inequality and systemic instability in global food distribution – an issue I hope to cover in my column next week. Polluting intensive chicken and pig units in mid-Wales are heated by burning timber. It is subsidised by government. How can we stop this craziness? Janniewannie You’re right, it is crazy. Intensive chicken and pig farmers often claim that they receive no subsidies. In terms of the payments we call agricultural subsidies, this might be true in some cases. But they often receive a significant subsidy in the form of the Renewable Heat Incentive. Farmers who install “green” heating systems in their chicken or pig units receive guaranteed and untaxed payments for 20 years. The handouts are so generous that their investments tend to pay off within five years: after that, it’s free money. The most profitable system is burning wood pellets. A large chicken shed uses approximately 120 tonnes of dry pellets a year. This means that each shed consumes a hectare of forest every year. These incentives have helped trigger a gold rush in eastern Europe. In Estonia and Latvia, even nature reserves are being clearcut for woodchip. In Romania, lovely Carpathian woods are obliterated, while in Poland logging companies keep trying to push their way into the ancient Białowieza Forest. In the years 2016-18, the area of European forest being felled rose by a remarkable 49% relative to 2011-2015. While the incentive scheme in the UK closed in 2021, the damage it causes will continue for the next 19 years. Oh, and incidentally, the incentive scheme is so corrupt that it brought down Northern Ireland’s parliament. But carry on, nothing to see here. I make charcoal using coppice wood from Somerset. The benefits of this old cycle are clear. I use the fine charcoal to improve the drought/flood resilience of my heavy clay soil, while sequestering stable carbon. Can this be scaled up, and what are the potential negative impacts? realfrankmate The first thing to say is that biochar can improve the fertility of soil and sequester carbon. So why, given that there was such excitement about it a few years ago, has it not yet been widely deployed? I looked into this while researching my book Regenesis, and the problem quickly became apparent. The cheapest source I could find in the UK cost £1,300 a tonne. You could compare this with agricultural lime, which is sometimes described by farmers as “prohibitively expensive”, and is generally applied more sparsely than the recommendations for biochar. My inquiries suggest that the average cost for a full load of lime delivered across 80km is roughly £50 a tonne. The only cheap way of obtaining biochar is to make it yourself, as this questioner is doing. But unless you get the burn exactly right, you’re likely to cancel any possible savings by releasing methane, nitrous oxide and black carbon, while the toxic smoke might shave years off your life. I wouldn’t recommend it. Having recently finished reading English Pastoral by James Rebanks, and read other articles on regenerative/rotational (basically old-fashioned) agriculture that is sympathetic with the environment, I’m of the view that this presents a solid compromise. Deveraux I’ve read English Pastoral, and while it is well written and interesting, I don’t see it as providing any useful answers to the predicaments we face. Remarkably, it contains no numbers at all: no indication, for example, of how much food per hectare is being produced on James Rebanks’s farm. Generally, old-fashioned farming of the kind Rebanks advocates is extremely low yield, and the methods he proposes in this book are likely to reduce yields even further. Low-yield farming means that large areas of land are required to produce our food. In other words, it is a formula for agricultural sprawl. The amount of land we use for extractive industries (principally farming) is arguably the most important of all environmental metrics, as this is land that cannot be used for forests, wetlands, savannahs and other wild ecosystems. It is the key determinant of habitat destruction, biodiversity loss and the drift towards extinction. One of my calls in Regenesis is that we become food-numerate: in other words, we begin to understand the numbers, on land-use, yield and other crucial issues. In an age of preservation at source, would shifting a lot of good living soil and water work as a patch and revive system alongside rhizosphere methods? goliver4 To extend the analogy between the rhizosphere and the human gut, like healthy and unhealthy gut biomes, soils can be either “suppressive” of disease or “conducive” to disease. When plants die, they can bequeath a legacy of the bacteria they have cultivated in the soil, protecting the plants that grow in following years. Some researchers have been experimenting with the agricultural equivalent of faecal implants. In other words, just as doctors take stool samples from healthy people and transplant them into the guts of unhealthy patients, they speculate that implanting suppressive soil into unhealthy, “conducive” ground could suppress pathogenic bacteria and fungi. It’s early days, and I will watch with interest. Intellectual property rights encourage innovation. What is the point in investing a great deal of time and money in developing farm-free foods if one cannot benefit from that investment? nick9000 There are several issues here. First, it’s not clear that exclusive intellectual property rights encourage innovation. For example, there’s strong evidence to suggest that compulsory licensing, which means granting poorer nations use of these technologies without paying prohibitive fees to the originators, far from smothering innovation, stimulates it. In several scientific fields, innovation is now obstructed by “patent trolls”: companies using the property rights they amass to demand ransoms from the innovators who want to work with them. Look at the case of Crispr gene editing. Second, these farm-free technologies are being developed with the help of public universities and public money. Is it really OK that we should pay for them twice? Third, we know from the rest of the global food system that patents encourage corporate concentration and drive the cycle of mergers and acquisitions. Not only does this cause major power imbalances, enabling a wide range of anti-competitive and predatory behaviour, but it is also likely to lead to the systemic instability of global food supply, which is beginning to resemble that of the financial system in the years approaching 2008. This is the issue I intend to explore in my column next week. Thanks everyone for all these interesting questions. George Monbiot will discuss Regenesis at a Guardian Live event in London on Monday 30 May. Book tickets to join the event in person, or via the livestream here. Regenesis: Feeding the World Without Devouring the Planet by George Monbiot is published by Penguin at £20 on 26 May. To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.