We need to rebuild the fertility and social capital that were once safeguarded in our family farm structure.
To work its wonders nature employs three main tricks. It is extremely diverse, tightly integrated, and makes do on low inputs - basically on what is around.
Certainly, it makes no use of fossil fuels. The sun and geothermal heat (with tidal power around the edges) provide all the energy that's needed.
Efficiency means diversity
Common sense and many a field and laboratory study show that diversity above all is the key to sustainability, resilience, and to what ought to be meant by efficiency - making best use of what's around.
When there are many different species side by side and each is genetically diverse, parasites and pathogens can't find a foothold in the way they can with today's monocultures. Demonstrably, diverse organisms interacting make far better use of available nutrients.
Diversity in farming translates into polyculture - mixed farming with genetically varied crops and animals, all raised synergistically. Low-input translates into organic, or something pretty close.
Diverse, organic or low-input farms when well managed can be among the most productive of all, per unit area of land. They are also among the most wildlife friendly. Clearly they are what the world needs.
Complex and skills-intensive
Such farms are complex - in general, the more complex the better. So they need to be skills-intensive - a lot more farmers will be required to run them.
When enterprises are complex and skills-intensive there is little or no advantage in scale-up and so in general they need to be 'small-to-medium sized enterprises', or SMEs.
In short, the farms that the world really needs, run along agroecological lines, should in general be small to medium sized, very complex and polycultural, and as near to being organic as can sensibly be managed.
Such farms would be quite productive enough and provide food of the highest quality while keeping the rest of nature in good heart.
These 'anachronistic' farms provide half the world's food
Already such farms, in traditional form, worldwide, provide 50% of the world's food - even though they have been sadly sidelined by the powers-that-be: treated as an anachronism. The industrial agriculture that soaks up most of the investment and research supplies only 30%.
Agroecological farms conceived as SMEs would also provide many millions of fulfilling jobs worldwide - including enough, in Britain, to soak up the million under-25s who are now unemployed or seriously under-employed.
We are often told that organic, small-scale, mixed farming is simply "unrealistic", a misguided exercise in nostalgia. Yet it is based on fundamental principles of biology and demonstrably works.
The ideology of industrial farming
In contrast, the industrial model now known as 'conventional' is pure ideology: absolute faith in high tech, geared to the maximisation and concentration of wealth.
It demands maximum output at what is perceived to be minimum cost: more and more agrochemistry to increase the yields from fields and crops and livestock that are already overstretched, with less and less labour employed.
This means there can be no complexity: monoculture must rule. All must be done on the largest possible scale to spread the costs. All outputs are conceived first and foremost as commodities to be sold on the world market to the highest bidder.
Speaking in January 2013 at the other Oxford Farming Conference, Environment Secretary Owen Paterson urged British farmers to produce more beef to sell to the growing Chinese middle class.
We should also export more biotech products, said Paterson, not because the world needs them, but because they are potentially lucrative.
This advice is perfectly in line with neoliberal thinking - but totally at odds with the principles of agroecology, common sense, and common justice.
Farming is for feeding people
Britain once had an agriculture well suited to feeding people. The development of mixed farming in the 18th century produced a step-change in farm productivity allowing a fast-expanding population to be fed.
So successful was the system that it lasted more than 200 years. At the end of World War Two much of lowland Britain was still occupied by family-run, small and medium-sized family farms.
Through good times and through bad they survived without pesticides or chemical fertilisers and with few subsidies from the state. At times of national emergency they were able to up their game and feed the nation.
And in times of hardship they were content to hunker down and wait for the pendulum to swing back. Together our family mixed farms were one of the nation's great assets.
The war against small farmers
For the past few decades governments, economists, supermarkets, agri-business corporations, even farmers' own leaders have waged a relentless campaign against family mixed farms, representing them as out-dated and inefficient.
Subsidies and the tax system have favoured the large-scale, mechanised, chemical-dependent unit. Markets for the healthy, nutrient-rich foods produced by mixed farms have been ruined by industrial commodity producers who have banked big profits and left taxpayers to pick up the tab for degraded foods and a polluted environment.
It's now clear that this nationwide experiment in chemical agriculture has failed.
Just as the banks are having to rebuild their capital reserves, we need to rebuild the fertility and social capital that were once safeguarded in our family farm structure.
Colin Tudge is a biologist with special interests in natural history, evolution and genetics, food and agriculture, and moral philosophy. The author of Good Food for Everyone Forever and Why Genes Are Not Selfish and People Are Nice, he is co-founder of the Campaign for Real Farming.
His latest venture is Funding Enlightened Agriculture which seeks to help new entrants to farming find start-up funds and become investment ready.