ECOLOGICAL PERSPECTIVE has taught us that all human activities, to be sustainable, must operate with cycling, that is to say renewable, resources. Agriculture is no exception. An agriculture that can sustain itself indefinitely must therefore have a built-in system to replenish the nutrients plants take out of the soil. We organic farmers have various ways of putting back organic matter, but often within a narrow perspective of robbing Peter to pay Paul, trucking in manure, fish fertilizer, seaweed, Chilean nitrate, blood and bone meal and the like without much regard for sustaining the biosystems that produce them, or for how long these resources might last, especially if all of agriculture were to begin using them. Even organic farms with major on-farm nutrient cycling programs often fail to consider the rate of soil nutrient cycling required to feed the human population densities of today's world, and at the same time rebuild the soil. And those of us who raise organic livestock often neglect their full potential as fertility cycling organisms.
Good Digestion
What are the primary requirements of soil nutrient cycling? The best description I have seen portrays the soil community in the organic farming ecosystem as part of the digestive apparatus of the plant community. The "underground livestock" of the soil community, though often microscopic, can throw their weight around: an acre of rich soil can carry an earthworm
population twice the weight of the livestock its pasture can support above ground. The soil community draws on soil organic matter both for nutrients which it eats and processes into forms plants can assimilate, and for carbonaceous material it can "burn" provide the energy to carry on its metabolism. It also regulates plant nutrient uptake, and breaks down or screens out substances that would be toxic to plants. In all these ways, the soil community serves plants just as the digestive and metabolic apparatus in our bodies, serves us. An even better parallel is the
ruminant, whose rumen microbial community is critical to its digestive process.
Indeed it is this view of the soil community as digestive apparatus that to me affords the most telling argument against the synthetic soluble fertilizers of conventional agriculture. For these fertilizers simply bypass this marvel of nature the way intravenous feeding of hospital patients bypasses a dysfunctional alimentary canal. The main difference is that doctors have
enough respect for normal digestive functions that they counsel intravenous only in emergencies, while the advocates of synthetic plant nutrition would routinely bypass the little understood natural miracles of digestion and metabolism.
If the recycling of nutrients and energy via soil organic matter production is vital to sustain agriculture, what then are our options? The rate of soil fertility production needed depends on the rate of depletion, which depends in turn on the food production demands being made - that is, on the human population each acre must support.
Enter the Ruminant
As long as global human population densities remained low, humans could simply hunt and gather Nature's produce and let her take care of the nutrient cycling. Which she did, at rates that varied from near total failure on the planet's natural deserts, to dramatic success on well-watered natural prairies like the eastern half of the North American great plains, where topsoil reserves accumulated many feet deep. We know that grass alone could not have generated all that fertility; it had to be a grass/ruminant complex. For left to its own devices grass quickly goes to seed and growth slows dramatically. And over time a thatch develops that further chokes growth and keeps seasonal biomass accumulation from contact with the moist soil needed to assure rapid decomposition. This dead mass of grass shades and delays the next season's new growth. Eventually less productive woody plants creep in to crowd the grass - sagebrush in our western plains, dyers broom (L.,genista) in southern Europe from the Pyrenees to the Caucasus, and in the British Isles heather or heath - whence heathen: people said to be uncivilized, presumably because they had yet to adopt either the lamb to transform their heathland or the biblical "Lamb of God" to transform their religious beliefs.
Enter the ruminant, which under ideal conditions:
1) keeps grass growing rather than heading out,
2) converts its biomass rapidly into a superior fertilizer,
3) breaks thatch and stirs the manure into the soil surface,
4) destroys heather and other brushy, "uncivilized" plants.
The grass/ruminant complex is thus a symbiotic chain leading from plant to animal and back to plant. And the work of microbial communities is crucial at two points in the chain: in the rumen, converting parts of plants into animal food, and in the soil, converting the excreted leftovers into plant food. Later I will describe an on-farm, domesticated version of this infinitely renewable, sun-powered system by which nature built the world's deepest topsoils. And I will argue that in today's world, with today's global population density, such a system must be part of any sustainable agriculture. But to understand why, we must first return to our hunters and gatherers and the beginnings of farming.
Three Traditional Systems
Before discussing how sustainable nutrient cycling can be achieved today, I want to describe briefly how it was done in three traditional agricultures operating under different constraints of climate, availability of arable land, and population density. Hopefully these comparisons will demonstrate the problems involved in achieving a truly sustainable system.
Tillage cropping is a soil depleting agriculture. The tillage itself accelerates the rate of soil metabolism, and can even waste organic matter if the crop nutrient intake rate cannot match nutrient output due to the increased biological activity of the stirred up soil. In areas of low
population density traditional agriculture sustained itself for millennia by moving the tilled acreage every two years or so. In West Africa for example, tropical heat accelerates soil metabolism to the point where it is hard to maintain soil organic matter reserves even with minimal tillage, so fertility reserves are built up in the living vegetation above the soil.
Often in this slash-and-burn system over 20 years of regrowth are needed to stockpile the fertility expended in a year or two of tillage. In such long rotations the cultivated fields eventually get too far way from the village, and so the village must change location. Sedentary farmers did
develop a loose symbiotic link with nomadic pastoralists to get their fields manured during the dry season, and this practice reduced the length of the rotation, and made it possible for the village to remain longer in the same location. The role of livestock in fertility maintenance was
rather hit-or-miss, but acceptable as long as population pressure on the land was low. Today the population per acre is much higher and the traditional farming system is no longer up to the task of feeding West Africa.
In the high desert of the Himalayas live the mountain subsistence farmers of Ladakh. Unlike West Africa, Ladakh has so little flat arable land that fields must be built from hillsides by erecting walls and filling in behind to create terraces. The difficulty of creating farmland makes rotations uneconomical, but even if the long rotations of West Africa were possible,
the harsh conditions in Ladakh would make vegetation accumulation so slow that little fertility would come from it. Instead Ladakhi farmers rely heavily on a variety of animals (sheep, goats, cows, yaks, donkeys, and horses) directly or indirectly for most of their basic needs. Primary
among these needs is fertilizer which they obtain by having the animals forage the steep, non-arable terrain, convert and concentrate their gleanings into manure, which is collected for use on the terraces. All of these animals are ruminants or close cousins (horse and donkey), and this
is the key to an agriculture that could have lasted indefinitely, had not Western development disturbed their traditional culture. In the harsh geographic and climatic conditions that make farming in Ladakh a marginal pursuit, a more aggressive domestication of the grass/ruminant complex was necessary, though population density was no higher than West Africa.
What happens when population pressure is much higher? In China for example, traditional agriculture needed to collect every scrap of manure from whatever source, human or animal, utilizing not only ruminants but every conceivable animal to process forage into fertility. China's recent turn toward artificial fertilizer appears to be a tragedy in the making, for a situation where agriculture is already operating at the upper limit of the land's capacity to provide food, the population increase supported by the input of synthetic fertilizer will last only as long as access to that resource, itself dependent on cheap oil. Worldwatch Institute, whose
business is to keep track of such things, puts the end of the cheap oil era within 20 years. Conceivably the Chinese might support the additional population with a more intensive domestication of the grass/ruminant complex. But before I get into that I'd like to end this brief planetary tour of agriculture with a look at the situation in North America.
The Lap of Luxury
Here at home arable land is plentiful, growing conditions good, population relatively low, and oil the cheapest in the world, so why worry? In the lap of such luxuries we have developed an extractive mentality with regard to agricultural and other resources that says: there's always more where this came from - what need to put anything back? Cotton fields in the
Southeast were depleted in less than a generation, so farmers extended the Cotton Belt westward, mining new land of its fertility and moving on. In the Northeast, farmers found tillage agriculture relatively unprofitable in the poor soils of New England, and gradually relinquished them to stock farmers, who eventually could not complete with the ranchers of the western high plains and the Rockies. This left much of the Northeast to the dairy farmers, and often farmland once tilled returned to forest. Meanwhile the great American mother lode of topsoil was discovered in the Midwest, often reaching six or eight feet in depth. But after less than a century of nearly continuous tillage this resource too shows signs of depletion. Finally, the southern Californian cornucopia is rapidly succumbing to the practically irreversible waterlogging, salinization, alkalinization, and water wars that have caused the apparently inevitable demise of every other hydraulic civilization on the planet (Babylon, Ceylon, etc.).
What all this destruction leaves is a North American agriculture highly dependent on
artificial fertilization, and thereby on cheap oil, whose known reserves appear to have a half-life of less than two decades. So I think we do need to worry.
Options
What are our options, both here and around the world? Organic farmers talk a lot about green manure, but I don't think it's up to the task. Doubling as a cover crop it's fine, but as a nutrient cycling scheme, it is too slow and inefficient , for several reasons. Firstly, land must be
partly removed from food production, or at least feed production, to grow green manure; most of the world can no longer afford that luxury and soon neither will we. Putting the green manure through a grazing animal yields not only fertilizer in a much enhanced sate, but food as well from the livestock. Secondly, both products are obtained without the energy and other costs of tillage. Thirdly, if Andre Voisin's classic on controlled grazing is correct, intensively grazed permanent forage, brought to its peak of performance by decades (if necessary) of grazing fertilization, out-yields any arable crop grown under similar conditions, sometimes by a
factor of two to one. This means that livestock capacity per acre, and therefore fertilizer production per acre, can be greater on permanent hay/pasture. And the fertility is achieved with a minimal energy cost, since no plowing, planting or machine harvesting is necessary, and the
usual costs of off-farm fertilizer production (extraction, processing, transport) are avoided. Voisin's productivity thesis depends on figures drawn from his native Normandy, and from the British Isles and the Rhineland, all cool wet climates that naturally give the advantage to grass
forage crops over those with higher climatic heat unit requirements, like the grains. He says the claim needs to be tested under other conditions. But New York State and much of the Northeast is also a cool wet climate where corn, for example, even as silage has been badly miscast as a
profitable feed crop.
The Workings of the System
How then, does an ideal on-farm fertility system work, and what is the current state of its art? Enter again the grass/ruminant complex, but no longer at the leisurely pace of Nature when she built the deep soils of Iowa. Now in its most efficient domesticated form, the complex becomes an agricultural system with three important components:
1) A rapid grazing rotation on permanent hay/pasture, with both plants and animals genetically adapted to the system;
2) A method of careful storage and composting;
3) A method of timely, non-wasteful distribution of compost back to the land.
The grazing system involves moving enough ruminants into a pasture to keep the forage from heading out and stopping growth, and yet moving them out rapidly enough so that:
a) new growth is not eaten, and
b) enough of the plants' photosynthesis factory is left intact to keep the grass growing at its maximum rate.
We control the process so that forage is grazed down to three inches and rested for regrowth up to six inches, or whatever upper and lower limits yield best for a given mix of animal and plant species. Part of the rotation acreage must be machine-harvested to keep up with early season
growth. Stock must be moved at least weekly, but investment in movable fence and watering equipment designed for the system is very cost-effective and reduces weekly labor to a matter of minutes.
Storage and composting of manure for highest yields requires:
1. Addition of carbon for the carbon/nitrogen balance necessary for efficient composting, and for the carbon recycling that will feed the soil community. A method used by farmers growing grain was to add grain straw to the manure as livestock bedding. But the more one denatures a ruminant's diet with grain feeding the soupier the manure, and the greater the amount of straw required. So at some point this method yields diminishing returns. Another traditional method requiring no grain culture is to make and feed enough hay that the stock need only skim off the best part, leaving the high cellulose stems to mix with the manure as bedding straw. This way both the stock and the manure get the parts of the hay that are best suited to each.
2. Addition of rock powders before composting or storage to chemically lock in ammonia and other unstable nutrients in the manure, to replace the small amounts of minerals lost in the products sold off the farm, and to get back the mineral balance as needed in some soils. Adding such rock powders as limestone and rock phosphate regularly to livestock bedding help dry and
sanitize its surface for the health of the stock, and in the composting phase, exposes the minerals to powerful chemical and bacterial activity that processes them into forms plants can use.
3. Finally, storage before and after composting that affords protection from rain leach-out and ammonia evaporation. The traditional manure pack built by constantly adding bedding to the manure deposited by animals over-wintered in the barn, works well in this respect. In fact,
barn preservation of winter manure in this way until summer composting is so good that it would be well to rethink the advantages of winter grazing in the Northeast. The harvesting, storage, and feeding labor saved must be weighed against losses of nutrients and pollution damage from winter pasture manure exposed to spring thaw run-off, as compared to well preserved barn manure.
Careful redistribution, the final link in our sustainable fertility system, requires that manure stabilized by composting be spread during the growing season when it will be best assimilated.
I have not described the fertility system in great detail because my intent here is to sell the necessity of a grass/ruminant-based agriculture, not teach the practice. Practical information on the grazing system is found in Andre Voisin's classic, Grass Productivity, and in updates by Bill Murphy and many others. For the latest word I rely on The Stockman Grass Farmer, a monthly edited by Allan Nation. Even the Extension and the Soil Conservation Service have begun to admit its economic advantages and are offering workshops. The federal ASCS incentive program now cost-shares some of the required fencing and livestock watering
systems. My article on the "Small Scale Integrated Farmstead" shows how the grass/ruminant complex can fit with other farm practices in ways that benefit the whole farm operation.
In summary, I would stress that the fertility scheme advocated here is the only one I believe will feed the world of today and tomorrow, because it is renewable, sun-powered, and uniquely capable of generating a generous surplus of fertilizer over and above the needs of the livestock supporting acreage (assuming little or no feed grain), which surplus can be used to
grow the fruits, vegetables, and grains that ought to be the staples of more human diets. And often the livestock supporting acreage can and should be non-arable land, as we saw in Ladakh.
I am not advocating that all fruit, grain and vegetable growers rush out and acquire ruminant livestock, but I do want to provoke some reflection on where our fertility comes from, and how long the whole system, including the fertility-producing source, can last. Regarding off-farm distribution of the surplus fertilizer this system is capable of, I see many options ranging from livestock farmers simply selling compost or raw manure to nearby growers without livestock, to more difficult but perhaps more efficient arrangements for interfarm cooperation where, for example, a dairyman and a neighboring veggie grower might team up to rotate their crops through the total arable acreage of the two farms.
But by this standard of ecological farming, most "organic" farms, including my own, are still transitional. For Northland Sheep Dairy I see a long, transitional process that uses sheep to rebuild an impoverished soil to the point where it can produce marketable meat and dairy products with no grain feeding, and sustain a limited acreage of cultivated food crops as well. It may take thirty years to bring this unpretentious Volusia hill soil to its full potential. In the long run it involves breeding animals and forage plants to fit the system: ruminants are primarily grass eaters and even today they will neither be healthy nor produce healthy food if that is not the bulk of their diet. But they have become funnels for grain. Too many people raise cattle and sheep nowadays as if they couldn't survive without grain, and many genetic lines have become that degenerate, and will have to be bred back to purely grass diets. Grain renders the system unproductive as a fertilizer factory; too much manure is consumed growing the grain.
A grain-fueled feedlot system grows most of the meat and dairy products in the USA. It has come under heavy fire lately, both from Worldwatch Institute, whose highly regarded annual State of the World reports on the sustainability of all resource-consuming human activity, and from Jeremy Rifkin's book, Beyond Beef. Unlike the ideology-heavy diatribes of the animal rights/vegetarian fundamentalist fringe, these are well thought-out ecological arguments, as far as they go. Unfortunately they both display an ignorance of agroecology typical of urban environmentalist writing: they both leave the reader with the impression that there is no ecologically positive role for livestock on the earth.
The urban environmentalists offer strong evidence that "the price of meat might double if the full ecological cost - including fossil fuel combustion, groundwater depletion, agri-chemical pollution, and methane and ammonia emission - were included in the bill "of raising livestock
according to conventional feedlot practices. In fact this essay was inspired in part by the desire to answer that argument by proposing an alternative to the feedlot, one which both produces meat and milk at little ecological cost, and offers it as a bonus by-product of a low-cost fertility generation system. But I fear organic farmers will not be taken seriously on this issue until we begin to put
our house in order. One place to start might be in a gradual revision of organic certification standards to reflect the latest ecological thinking.
We could go on record that feedlot ruminant production (including concentrate-heavy confinement dairy) fails to be sustainable on the following counts:
- It breaks the grass/ruminant soil fertility cycle that is the most efficient way of feeding the soil using largely renewable resources, that is known to man.
- The manure from the feedlot system is not only wasted, it becomes a major pollutant.
- The feedlot system is to blame for the fact that, of a national manure production estimated at anywhere from 80 to 180 million tons, only 2-3% is carefully recycled. This is an enormous waste of a primary national resource.
- Growing livestock in pens far from the source of feed depends, in the case of ruminants, on replacing their normal forage diet which they have evolved over millions of years, with a diet heavy in concentrates. This causes ill health, not only in the grain plants and the soils that feed
them, but in the livestock and in the human society that eats such poor quality, over-fat meat.
- The feedlot system, like monoculture and big dairying, concentrates too much of one thing in one place: too many animals, too much manure, feed, rodents, flies, and disease. Here, as in all agricultural systems, scale of operation needs to be considered as a criterion for health and
sustainability. Like much large scale agriculture, feedlots look like industrial disasters, unsurprisingly, for they represent attempts to apply industrial structures and methods to biological systems to which they are ill-suited.
Some organic livestock standards gradually phased in to remedy this situation might be:
1. Forage (grasses and other high cellulose plants) as a percentage of Dry Matter Intake is required to be nearly 100% for all ruminants. Concentrate diets are prohibited for the same reasons as growth hormones and other unnatural production stimulants
that push the ruminant organism beyond its normal capacities and into ill health.
2. Ruminant livestock must be range-fed or at least be raised close enough to the source of feed to permit manure recycling.
3. All livestock manure/urine must be recycled. It may be recycled partly to other farms than the sources of feed production, but in any case sufficient care in storage, composting, and spreading is required to maximize nutrient retention and return to the soil.
In conclusion, I have tried show how ruminant livestock are essential to agriculture and therefore to human survival in many parts of the world, and I have argued that North America, too, though favored, will eventually have to rely on the grass/ruminant complex. In the words of Allen Nation, "The farmer who believes his land is too good for grass eventually produces land
that is no good for anything."