Grazing

• 1. Introduction

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  Grazing is the oldest continuous food system on Earth, predating cities, writing, and fixed fields. Before the first permanent human settlements rose around 7000 BC, sheep and goats were already moving with nomadic peoples across open land, converting grass into meat and wool. That relationship between animal and landscape has never stopped. Today, grazing systems cover about 60 percent of the world's grassland, which adds up to just less than half of the world's usable surface. For an estimated 100 million people in arid regions, raising grazing livestock is the only possible source of livelihood. So what makes grass worth all of this? How did a simple act of letting animals eat become one of the most consequential land uses in human history? And what happens when that ancient system runs up against the limits of the planet it depends on?

• 2. Nomads and Settlements

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  Sheep were the first animals brought under human management, followed closely by goats. Both species suited people who were always moving. Cattle and pigs came later, domesticated around 7000 BC, once communities had settled into fixed locations that could support them. The great Eurasian steppe became the proving ground for a way of life built entirely around mobile herds. Across inner Asia, horseback nomads migrated their sheep and horses between pastures across the seasons. Nomadic empires rose and fell on this foundation across centuries, right through to the early modern period. Then, during the late medieval and early modern era in England, a different kind of transformation took hold. Common lands that peasants had farmed for crops were enclosed and converted to pasture by landed gentry, all in service of the wool trade. On commons in England and Wales that persisted, grazing rights were tightly defined by number and type of animal and by the time of year when those rights could be exercised. The occupier of a particular cottage might be permitted to graze fifteen cattle, four horses, ponies or donkeys, and fifty geese, while the numbers for their neighbours would likely differ. When overuse threatened a common, access was restricted further rather than allowing the land to degrade. In America, livestock were grazed on public land from the Civil War onward, and the Taylor Grazing Act of 1934 was enacted after the Great Depression specifically to regulate how that public land was used.

• 3. Systems Built on Recovery

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  Continuous grazing, where animals have access to the same area throughout the year, is the simplest approach but the hardest on the land. Every more sophisticated grazing system is built around one core idea: rest. Rotational grazing divides a range into several pastures and moves livestock through them in sequence, giving each section a recovery period. Deferred rotation takes this further, keeping at least one pasture ungrazed until after seed-set so grasses can reach maximum growth before animals return. Rest rotation goes further still, resting one pasture entirely throughout the year while livestock rotate among the others. Ley farming takes the logic off the pasture altogether, alternating between fodder crops and arable crops on the same land over time. Mob grazing, invented in 2002, pushes the concept toward extremes: very large herds on land left fallow far longer than usual, with advocates arguing the approach is more sustainable. Patch-burn grazing takes a different route entirely. It burns a third of a pasture each year, regardless of how large the pasture is. The burned patch draws in cattle or bison because fresh grasses grow there quickly. The remaining patches receive little to no grazing while the burned area is being worked. Over the following two years, the next two patches are burned in turn, and then the cycle begins again. Each patch effectively gets two years of rest between heavy grazing episodes. The Tallgrass Prairie Preserve in northeastern Oklahoma has been managed this way with bison herds for over ten years, restoring the bison-fire relationship across a landscape of 30,000 acres.

• 4. What the Land Requires

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  Grazing management holds two goals in tension at all times. The first is protecting pasture quality against overgrazing, keeping the land capable of production season after season. The second is protecting the animals themselves from hazards specific to grazing, including grass tetany, nitrate poisoning, trace element overdose from molybdenum and selenium, grass sickness and laminitis in horses, and milk sickness in calves. Beyond the individual farm, well-managed grazing can do things that look more like ecological restoration than food production. Grazer urine and feces recycle nitrogen, phosphorus, potassium and other plant nutrients back into the soil. Trampling aerates the soil. In tallgrass prairies of North America, the ecosystems are controlled largely by nitrogen availability, which is itself shaped by interactions between fires and grazing by large herbivores. When grasses grow after spring fires, herbivores preferentially graze them, producing a system of checks and balances that supports higher plant biodiversity. In European heathland, that cultural landscape can only be maintained by continuous grazing from cattle, sheep, or other grazers. Conservation grazing deploys this logic deliberately, using rare and native breeds for their hardiness to improve biodiversity at a site. In some cases, English Longhorn and Highland cattle are brought in specifically to re-establish traditional hay meadows. Agrivoltaics is a newer application of the same principle. Grazing under solar arrays provides shade for both animals and vegetation, retaining higher soil moisture and reducing the need for mechanical mowing. More than 100,000 sheep graze at solar installations across the United States, primarily in the South, with the American Solar Grazing Association working to spread best practices for the combination.

• 5. Costs Written on the Land

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  Grazing occupies 26 percent of Earth's terrestrial surface, according to the Food and Agriculture Organization. Feed crop production for livestock requires about a third of all arable land. Expansion of grazing land is a leading cause of deforestation, especially in Latin America, where roughly 70 percent of previously forested land in the Amazon basin has been converted to pasture. The Center for Biological Diversity has documented what extensive livestock grazing has done to arid lands in the southwestern United States: native vegetation destroyed, soils damaged, stream banks eroded, waterways contaminated with fecal waste. Once-lush riparian corridors reduced to dry, flat wastelands. Once-rich topsoil turned to dust. In 1990, Arizona's state park department reported that over 90 percent of the original riparian zones of Arizona and New Mexico were gone. A 1988 Government Accountability Office report estimated that 90 percent of the 5,300 miles of riparian habitat managed by the Bureau of Land Management in Colorado was in unsatisfactory condition, as was 80 percent of Idaho's riparian zones, with poorly managed livestock grazing identified as the primary cause. The climate picture adds another layer. A 2013 FAO report estimated livestock were responsible for 14.5 percent of anthropogenic greenhouse gas emissions. In New Zealand in 2004, methane and nitrous oxide from agriculture made up somewhat less than half of the country's total greenhouse gas output, most of it from livestock. Research comparing grazing cattle with feedlot cattle found grass-fed animals produce far more methane. One study published in the Journal of Animal Science found grass-fed cattle produce four times as much methane, attributing the difference to the high-fiber, low-quality diet rather than any characteristic of the animals themselves.

• 6. Feeding the Margin

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  Grazing supplies about 9 percent of the world's beef production and about 30 percent of the world's sheep and goat meat, according to the Food and Agriculture Organization. Those numbers are modest fractions of total production. But the question of who depends on grazing, not just what it produces, points somewhere else entirely. For the estimated 100 million people living in arid regions, and likely a comparable number in other zones, grazing livestock is not a choice among many food systems. It is the only viable one. Lands that cannot support arable farming, where soil or climate or terrain make crops impossible, can still support animals that convert grass into food. That conversion is the original and still essential logic of grazing: taking cellulose that a human gut cannot process and transforming it through livestock into meat, milk, and wool. The question of how to maintain that conversion without destroying the land that makes it possible has occupied farmers, range scientists, and regulators for as long as the practice has existed. The Taylor Grazing Act of 1934 was one answer for the American West. The stinting system on English commons, limiting each commoner's herd when overuse threatened the land, was another answer worked out centuries earlier. The patch-burn cycle at the Tallgrass Prairie Preserve, restoring a bison-fire relationship across 30,000 acres, is one more answer being tested right now.