Oklahoma ranchers set a third of the prairie alight each year to mimic ancient bison
On Oklahoma's Tallgrass Prairie Preserve, managers burn a third of the pasture each year and let bison crowd onto the fresh regrowth, leaving other patches to rest. The trick recreates an ancient partnership between fire and grazing herds, and shows that grazing can heal land as well as wreck it.
Grazing turns grass and other forage, whose cellulose people cannot digest, into meat, milk and wool by letting livestock roam and feed on wild vegetation. It often uses land unfit for crops, though fields are sometimes turned over to pasture when animals pay better. The practice is as old as farming: sheep came first, then goats, both suited to nomads, while cattle and pigs followed around 7000 BC once people settled. Across the Eurasian steppe, moving flocks of sheep and horses fed the horseback nomads whose empires rose and fell into early modern times.
The stakes are large. By an FAO estimate, grazing systems cover about 60% of the world's grassland and yield roughly 9% of global beef and 30% of sheep and goat meat, and for some 100 million people in dry regions, plus probably as many elsewhere, herding is the only viable livelihood. Badly run, it drives deforestation, wildlife loss, polluted streams, soil damage and desertification. Good management protects both pasture and animals, which can suffer from overdoses of trace elements such as molybdenum and selenium.
Farmers choose from many schemes. Continuous grazing leaves animals on one area all year; seasonal grazing rests land for part of it; rotational grazing moves herds through a sequence of paddocks. Rest rotation keeps at least one of four or more pastures idle for a full year, deferred rotation waits until grasses have set seed, and ley farming swaps pasture with arable crops. In patch-burn systems each burned third gets two years of recovery, giving prairie plants and birds a patchwork of habitats; the Oklahoma preserve has run it across 30,000 acres for over a decade, and Devon heathland burners call it swailing.
Rules for sharing grass have a long history. On English and Welsh commons, each cottage might hold rights to graze a fixed number of cattle, ponies and geese, while the New Forest charges a yearly fee per animal turned out; overused commons were stinted with tighter caps. Late medieval enclosures turned peasant farmland into gentry sheep pasture for the wool trade, and in the United States the Taylor Grazing Act of 1934 finally regulated grazing on public land.
Source: Grazing
