Is Farming Sustainable?
[ Many of the articles on this site have suggested that renewable energy technologies will likely provide, at best, only partial solutions to Oil Peak and the depletion of other fossil fuels. Some major lifestyle shifts are necessary and inevitable if we are going to learn to live with less energy. Modern farming, through industrialization, has become incredibly energy intensive as well as damaging to topsoils and water tables. But earlier methods of farming may have been unsustainable also, even if it sometimes took centuries, rather than years, for the problems to reveal themselves. In the following post which first appeared on the RunningOnEmpty2 e-group, Arthur C. Noll considers the reasons why, and helps enlighten us about some of the challenges we may face in moving towards sustainable local sufficiency in a post-oil-peak era. - AF ]
"Is farming sustainable?" This is a complex question that we have gone over and over, but it seems we need to keep going over it. Maybe we could agree on something that would go in the files. I've taken a little more time than usual to write this, and I'm going to keep it on file myself, not lost in my out box, either, :-) I want to try to stop rewriting to this question over and over. Maybe others can spot things I've missed.
First we need to define what we are talking about. For me, farming consists of killing existing wildlife and vegetation in an area, and bringing in other plants and animals that would otherwise not live there, and trying to maintain this state indefinitely. This leaves out slash and burn, because it doesn't try to maintain the area that has been cleared. Herding brings in animals that might not do well on their own, but doesn't try to completely kill existing vegetation or animals, though of course existing animals will be competition, something must give, though it doesn't have to be extermination. Both slash and burn, and herding, have their potential problems, but I feel they are not the same as farming, and we can talk about them separately. The plants that are usually brought in are annuals, the plants killed are usually perennials. People like the annuals because they tend to put growth into large edible seeds, tubers, roots, fruit. Perennials tend to put growth into more roots, stems, leaves. This is not an absolute thing, many perennial plants also produce abundant edible seeds and fruit, especially with regard to trees and bushes, but for smaller non woody plants, the annuals and perennials generally divide this way. To begin with I'll stick with the problem of growing plants, and deal with the farm animal question later.
People are usually talking about two basic systems of farming on this list. One way, after clearing trees and shrubs, is to heavily mulch an area. This destroys competing weeds and grass, and slowly feeds the soil and the plants you want, as it rots away on the bottom. It conserves water in the soil and prevents erosion. On the down side, it takes a considerable amount of mulch to make this work, a lot of cutting and hauling, and you can be taking the growth of vegetation from a big outside area to do this. If the mulch isn't thick enough, weeds and grass will grow through it. The mulch can harbor plant diseases, insects, rodents, which can do considerable damage to crops. It can keep the soil cold longer in the spring. (But it can keep the soil from freezing in the winter, too) Though erosion is not usually much of a problem, soil nutrients can be leached away far more readily than with perennials, since the root system of annuals doesn't have time to grow as extensively. Even perennial plants like grasses can lose nutrients in a climate that would normally grow trees, they do not make a root system with the depth that trees do. So the mulch has to keep coming, year after year, to make up for this loss. This is a potential factor for unsustainability, but not the final word on it. More later.
The other way of farming is more commonly done, which is to plow the ground, physically turn it over and kill the existing vegetation. The ground will warm up faster this way, but it will also dry out faster. The bare soil doesn't give a home to diseases, insects, and rodents like mulch sometimes does, (some people apparently go long periods without much trouble this way, others have trouble quickly) but it makes the soil subject to both erosion and leaching. Fertilizer from outside must be added frequently. Weeds, grass, tree seedlings, will readily take root and have to be removed. Often the soil is full of weed seeds just waiting for the proper conditions to germinate, and cultivation brings crop after crop of weeds. Plowing can be compared to scratching or cutting skin. Weeds are like nature's scab, to heal the damage of perennial cover being broken, to stop erosion and leaching away of nutrients.
So both systems tend to lose soil nutrients much faster than would be leaving the area if covered in native perennial plants. As said before, this is a serious factor towards unsustainability.
This doesn't say it isn't sustainable, though. Fertility also tends to renew, via several different ways, at varying rates depending on geographic location. If one can take from a wide enough area around the cultivated crop -and I will refer to both mulched and plowed systems as "cultivation"- and slow down losses from the cultivated area enough, it might be that one would have a sustainable system. It is not done successfully very often, but in theory it can be done. There are also ways to slow down nutrient loss. Maintaining presence of a large living root mass by careful attention to planting successive crops of annuals is one way, but this runs into a problem in temperate areas. Cover crops are sometimes grown in the winter to try and solve this problem, but it takes more energy to plant this extra crop, and more energy to plow it back in. The amount of energy needed is a serious factor in sustainability, as well as holding on to soil and nutrients. The mulch system loses out with this method, as before it is preventing erosion, but not preventing leaching. Living mulches have been tried, but living mulches become competition for the crop. Having the crop cover all the soil in wide beds is also a solution to packing the soil with roots and preventing nutrients from escaping, and increasing yields. This system does not lend itself to large scale growing, using animal draft or machinery, but does seem to work well on small scales. However, labor to do everything by hand becomes a consideration. The amount of land needed to feed people varies according to fertility, water, and climate. Moving towards the tropics can mean two or three crops a year, while as you move to the poles, it becomes one season, and that one season becomes shorter. Fewer crops per year means more land must be used, and more energy needed.
Recycling all the plant matter back to the soil is important, including what has gone through people and other animals. This increases the chances of sustainability.
Soil nutrients have a cycle similar to the water cycle. You probably remember the water cycle from grade school. Water evaporates from the ocean, rains down on land, collects in streams and rivers and back to the ocean. That simplifies it quite a bit, water is also evaporated from the land and from plants, but is basically true. Soil nutrients are also moving downstream, both in macro form, bits of soil eroding and flowing downstream, and also on the micro level, nutrients leached into solution. Without the addition of people and cultivation, it happens but usually goes very slowly. Perennial root systems, natural litter of dead leaves and grass, holds both water and soil nutrients quite effectively. And also soil nutrients are coming back from the ocean, also quite slowly. Fish swim upstream to spawn, they are often eaten by birds and animals that often defecate on the land, pushing those nutrients further up the watershed. Seaweeds also get eaten by animals who in turn defecate and die on land. An animal may eat plants at a low level in a watershed and move uphill before it defecates, or dies. They may go the other way, too, but some animals will consistently move fertility uphill. The land is richer going towards the water, so it is natural for animals to eat there, but what attracts animals also attracts predators, so animals may tend to eat at low levels, and rest, digest and excrete in less abundant areas up the watershed, constantly moving fertility uphill. So there is this constant slow movement of soil nutrients towards the ocean, and it is also coming back, away from the ocean.
There is also new soil being formed all the time by rocks weathering and breaking down. Plate tectonics cause land to be lifted up in mountains, volcanos grow. As they break down, soil is created. It is a very slow process. But without life holding onto the soil, rain would wash just about all of it to the ocean. We have a legacy of many millions of years of soil accumulation, held by vegetation, that can be lost in an extremely short time, relatively. There are areas of the world that have been eroded down to bare rock as the result of farming, many feet of soil lost in 1200-1500 years.
Nitrogen is a vital plant nutrient, it is required for making proteins, (also vital for people, obviously) that has somewhat different cycling, going between the atmosphere and the soil and all the living things. There is a high energy requirement to make atmospheric nitrogen (N2 must be broken into separate nitrogen atoms and bonded to other elements, and the bond is very strong) available to plants and then to animals. It happens naturally with lightning, and with various bacteria, both living alone and also in symbiosis with various kinds of plants, the legumes and the actinorizal plants. Like the other nutrient flows, there are rates at which it happens, and it is hard to change these rates.
People can add their own efforts to this, gathering seaweed, dead fish, scraping sediments, and returning them to the land. Very large quantities of nitrogen fertilizer have been made in the last 75 years or so, using fossil fuels, and also people have been mining deposits of other nutrients. These last efforts are going to be severely cut back. The question is then how much energy people have to spend on moving nutrients around, all eventually without the help of fossil fuels. It becomes a question of how much land is available to take mulch or manure from to feed farms sustainable. It is once again that matter of EROEI, the energy returned on energy invested. All forms of life must have a positive EROEI, otherwise it is dying.
Obviously, the closer you are to bodies of water, then the easier it is to have a positive EROEI with regard to this. It will cost you less energy to move seaweed and fish waste a few feet if you have fields close to the ocean, than if you are miles away. Most sustainable agriculture systems have been close to water, typically on the flood plains of rivers, and nutrients either brought down from above by flood waters, or recycled from the water with water weeds, fish waste, sediments, or both. Cultivation too far away from good sources of fertility has usually proved to be unsustainable over time, more than once it has completely destroyed the soil in large areas.
The activity of wildlife is also a double edged sword, when it comes to the sustainability of farming. The most fertile areas are fertile partly due to the large activity of wildlife around water. But large flocks of birds, large herds of animals, find cultivated crops to be tasty, too. The competition with wildlife and farms can be a serious issue. People have guarded their crops with human guards, dogs, and fences. All can work, all have potential drawbacks. Quite often animals have been exterminated as a "solution". Some animals like rodents and rabbits have been extremely resistant to being killed off, and still do large amounts of damage.
This leads to the subject of farm animals. Here is a list of the problems I can think of with farm animals
1. They must be penned or fenced, and this is energy expensive, to build and maintain pens and fences capable of the job. "Cheap" steel from using fossil fuels has been common in the last century or so to do this job.
2. Food and water must be brought to them and manure taken away, also energy expensive.
3. If the food comes from farmed land, there is a question of whether it would be more efficient for people to eat the food instead of animals who convert it to milk and meat at a loss.
3. Parasites tend to build up when animals are not allowed to roam as they want. Diseases can be readily passed by animals in close quarters, and may also get into the soil or buildings.
4. Animals will often require surgical modifications to allow them to live in close quarters, castrating males, dehorning animals. Lack of exercise can also bring a need for trimming hooves. These kinds of modification have an energy cost.
The upside of all this energy investment is that there is little effort to catch animals for slaughter, and the animals can convert forage resources that people cannot eat directly. The animals are kept under control, they are not eating crops, wandering in roads, tearing down clothlines, etc. But it is probably fair to say that without fossil fuel, penned animals in farming communities have been too energy expensive for most people to afford to eat much meat. Whether that is good or bad is another subject. Populations of people have lived on diets very low in animal products, as well as very high, quite possibly there are selections that go on with this, and efforts to categorize what is a healthy diet for everyone is probably impossible. It is an important question for sustainability, obviously if a diet makes you sick, you aren't sustainable on it.
To sum up, these are the factors I see involved with the sustainability of farming.
1. The nutrient cycle, roughly following the water cycle.
2. The threat to crops from the animals pushing the nutrient cycle.
3. New soil formation from mountains and rocks breaking down
4. Distance from bodies of water
5. Specific methods of cultivation and social culture, like using humanure, that recycle nutrients more times before they are lost, prevent erosion and leaching.
6. energy needs to do #5 and protect from #2
7. Human population not allowed to exceed the nutrient flow that can be maintained with the above.
An example of what I believe is sustainable farming is"One Straw Revolution", by M. Fukuoka. I believe this book can be found in the Soil and Health Library on the web. Fukuoka worked out sustainable flood plain growing of rice and barley, no cultivation, no prepared compost, no synthetic chemicals or fertilizers. What sort of inputs he was getting from upstream is difficult to say, but he probably was getting some. In the uplands he grows trees and encourages semi wild vegetables. There are a lot of other good books and essays in the Soil and Health library, and also lots of other books about soils and management techniques.
My own conclusion should be obvious, it is what I've often posted. Near bodies of water farming has a chance to be sustainable using methods similar to Fukuoka's. He has not had to deal with healthy wildlife populations, though, and if larger numbers of wildlife returned, the energy to guard crops would have to be increased, would probably require community effort. Upland temperate areas will likely be sustainable to work as slash and burn with very long rotations in woodland areas, with hunting as the main source of protein, and in grasslands, semi nomadic and nomadic herding and hunting. Tropical upland areas might be sustainable with careful management to mimic perennial root systems by planting time overlapping annuals in beds, and careful recycling of everything. But I would call this experimental at the moment.
Some parts of the world have annual plants growing naturally. Annuals are often similar to weeds in growing in disturbed areas, but they also evolved to survive conditions that would kill even perennials. Making a large seed to survive long dry seasons and then get a fast start when rains come again is another annual plant survival strategy. I never saw any annual plants growing wild in New England, but I see them here in Central California. Along with plenty of perennials. So it might be possible to grow grains here, and in similar places, without plowing or mulching. Fukuoka gives as a guiding principle to look at the land, look at what is growing there, and try to fit in. For the most part, fitting in does not consist of completely killing off the life in an area with the idea of keeping it out permanently, and growing other things.
Arthur can be emailed at arthurnoll(at)onemain.com (replace (at) with @). He lives in Sacramento, California, USA.