Most food now comes from large farms that focus on just one or two crops or animals. This kind of farming requires constant inputs: fertilizer, pesticide, water, animal feed and other resources. It also produces a constant output of pesticide-contaminated water and other waste.
It is sometimes assumed that growing food without fertilizers, pesticides or other chemicals that have unwanted consequences means growing them without any yield-increasing methods at all . According to this argument, we need higher yields to feed a growing population, and we need chemicals to boost yields; organic agriculture is equated with low-yielding agriculture. However, there is an alternative farming method that is both high-yielding and organic. This method is permaculture and it uses ecological methods instead of chemical ones to boost yields.
Many experts have stressed that to sustain a growing population in a way that is viable in the long-term, we need is sustainable intensification . This refers to a method of agriculture that gives higher yields than industrial monoculture, has less impact on the environment, uses less water and requires fewer inputs. Happily, sustainable agricultural practices also tend to be more productive than non-sustainable ones. An analysis of 286 sustainable farming projects in the developing world found that yields doubled for most plants . Permaculture is a system that uses many sustainable intensification technologies together.
Sustainable intensification is being implemented all over the world, with a 50% increase in four years , and with entire countries like Cuba and Bhutan moving to sustainable systems.
No inputs, no waste
Whereas industrial farms import inputs such as fertilizer and remove waste products such as pig effluent by mechanical means, permaculture designs the farm so that all inputs are provided on-site by another species, and all outputs are put to use. For example, a cow requires an input of grass, and creates an output of dung and urine. By spatially juxtaposing the cow and the grass, the cow's feed is provided by the grass and the grass's need for fertilizer is provided by the cow's manure and urine. This slashes the need for human or mechanical labour. A permaculture farm is an interconnected system of flora and fauna that recycles its own resources - an agroecosystem. In contrast with the large fields of single crops seen in industrial farming, permaculture favours complex patterns where different species are closely juxtaposed in space and time, allowing these synergistic interactions to happen.
Integrated pest management
Species need protection from pests and predators. In a permaculture farm, this too is provided by other species, thus removing the need for artificial pesticides. This is known asand can solve our problems with pesticides leaking into the environment.
Industrial-style farming techniques deplete 6-24 kilos of soil for ever kilo of food grown . This is a perfect example of a failure to think long-term; growing food in a way that diminishes the land's capacity to grow food is like killing the goose that lays the golden eggs. Permaculture (as its name suggests), focuses on the long-term fertility of the soil. Permaculture can create 20 kilos of newly fertile soil for every kilo of food grown. Ensuring that soil has a thick spongy texture has immense consequences for world water use.
Permacultural animal husbandry
Ranching is often blamed for environmental problems because it uses a lot of land and water, can require large amounts of grain feed, antibiotics which leach into the environment and produces runoff that can pollute local water supplies. One argument against ranching is that it requires 16 kilos of grain to produce one kilo of beef, so to preserve food and avoid a food crisis, we must all become vegetarian .
[[Image:Tessellation.jpg|thumb|left|A large percentage of the world is covered by unvarying grass pastures with cattle dotted around. We can increase the productivity of this land many times over by dividing it up into small cells
The farm in the picture is also using silvopasture - growing trees on pasture. The leaves provide extra feed for the livestock, and the trees can also produce fruit, nuts or timber.
All these points are valid criticisms of extensive grazing and feedlot farming. However, there is a way of raising livestock that is more in harmony with evolution's design. It is called mob-grazing, cell-grazing, or an 'animal tractor' and works by imitating the natural grazing patterns of herbivores.
In the wild, herbivores huddle close together for protection from predators. In this 'mob', they mow down an area of grass in about a day, then move on to a different patch. The loss of predators has meant that herbivores spread out into a different, extensive pattern of grazing. This caused overgrazing and the destruction of grasslands in large parts of the world. The carbon released by the degeneration of these grasslands is a greater than from all the fossil fuels burnt by industry, prompting authors of a recent paper in Science to say that the loss of predators "may be humankind’s most pervasive influence on nature" .
Mob-grazing restores natural grazing patterns, so grass grows the way it evolved to grow. Using light, portable electric fencing, livestock are corralled into a small 'cell' of grass at very high densities. After 1-3 days grazing, the herd is moved to a different cell. Any one area of grass is only grazed a few days per year and spends the rest of the time growing, so there is no overgrazing, despite extremely high densities of livestock.
The benefits of this sort of grazing — for grass, for soil, for animals and for people — are remarkable. Manure fertilizes the grass, the mowing causes the grass to shed some of its roots, which then decompose and further improve the soil, and the animals' hooves break up the hardpan on the surface, further improving the structure of the soil. As mentioned in water-efficient agriculture, mob-grazing has been shown to increase the amount of water soil can hold by 775%. The name 'animal tractor' is apt; the herbivores mow and cultivate the ground more effectively than tilling, while also producing meat. This cultivation is particularly needed in sub-Saharan Africa and other places where extensive grazing patterns have made grasslands dry and dead. Anywhere that cell-grazing has been implemented, grasslands have recovered and the soil and ecosystem holds so much water that drought is no longer a threat.
Another key advantage is that multiple animals can graze the same pasture in rotation. Polyface Farms grazes cows, turkeys, pigs, chickens, hens and rabbits on the same space by rotating them in time. This further benefits the soil and allows the animals to benefit from one another. For example, the maggots that grow in cow manure are a food source for chickens. Moreover, it obviously allows much higher productivity per unit of land.
The argument that conversion of feed to meat is inefficient does not apply here, because in such a system cows only eat grass and weeds, not grain or anything else that is edible by humans. Therefore no useful food resources are being wasted. Besides, beef from grass-fed cows has a better nutritional profile than from grain-fed animals and is universally considered tastier. Cows also convert grass to meat much more efficiently than they convert grain. Similar logic applies to other kinds of meat. We could say that in agroecology, the purpose of animals is to convert inedible grasses, insects, leaves etc. into edible meat. If we are to build a food system that provides high-quality food to all of humanity, it is essential that we use the 335.7 trillion m2 of pasture available to us for raising meat sustainably by converting these inedible grasses into meat. One estimate is that this would provide enough food for 1.3 billion people.
Productivity of permaculture
Permaculture is not only an ecologically sound means of food-production, it is very productive. Permaculture expert David Blume makes a convincing case for the productivity of permaculture, writing, "In a good but somewhat sloppy design, you need about 500 square feet (46.5m2) per person maximum. In a very good design, 200 square feet (18.5m2) will do the job." John Jeavons (father of another school of permaculture called biointensive agriculture), makes more conservative claims of around 316-372 square meters  .
The 2011 UN report on the right to food notes that agroecology initiatives typically double yield within ten years while reducing the need for inputs like fertilizer. It also reports that agroecology projects generally come about as a result of peer-to-peer collaborative sharing of farming knowledge.
While not as automated nor as productive as the aeroponics techniques described to the left, agroecology is a highly practical and advanced methodology that can play a role in making Spaceship Earth work for everybody. In time, it may become possible to automate agroecology by using sensors to detect when plants are ready for harvest, and having robots that can pick vegetables, prune trees and so forth.