Domesticated livestock are typically contained in a large pasture and left there to forage year-round in a process known as "set stocking". Contrast this with natural herds of herbivores, such as the bison that once roamed the Great Plains and were free to move-on as soon as the forage became scarce or inedible. In set stocking, the livestock naturally seek the most tender shoots of grass, continuously clipping and weakening the new growth and leaving the old growth to mat and inhibit any re-growth. The result is a thinning of the grass cover and a reduction in the mixture and diversity of the grasses. In the more natural free-ranging grazing approach, the large animal herd places intense pressure on the grass for a brief period of time, consuming everything down to a level where it becomes less palatable and then moving on and leaving the area to rest. This provides the grasses with the optimal growing environment, leaving plant residuals that sustain growth and opening the canopy to let in sunlight to promote root growth, reseeding, and grass stand thickening. Management Intensive Rotational Grazing (MIG) is a farming practice that emulates this natural order and was traditionally practiced in Europe, where land was scarce.
In MIG, the pastures are divided into smaller paddocks that can sustain a herd of animals for a few days. The extent of pasture divisions is determined by many environmental factors, including; herd size, grass swards, soil richness, rainfall, and time of the year (i.e. re-growth rates.) Livestock farmers then keep a watchful eye on all the environmental factors that determine grass levels, and move their herd through the paddocks as though emulating a naturally range grazing herd. A MIG farm looks very different than a set-stocked farm. The grass is clearly shortest where the livestock has just been and longest in the paddock just ahead of them, but everywhere it is lush and thick. Contrast this with a set-stocked pasture that is rubbed bare in places and overgrown with weeds in others, belying the inherent imbalances in the soil beneath. MIG farms also look different in that there are miles of cross-fencing (both permanent hi-tensile wire and temporary polywire) that the farmer uses to reduce the size and shape of the paddocks and to adjust to the environmental factors. This fence and cattle need to be moved frequently, to provide the livestock with optimal forage and the grass with optimal growing conditions. Hence why this form of farming is often referred to as "management intensive" grazing. In fact, among this resurgent breed of farmer, you are far more likely to hear them refer to themselves as "grass farmers" than as "ranchers", as their non-MIG counterparts like to be known.
MIG farmers are more likely to be out in the pasture, walking among their herd and looking for any early signs of health problems while moving the fences an/or the herd. Contrast this with the traditional rancher who set-stocks his livestock, visits them infrequently in a pick-up truck or ATV, and relies upon chemicals and external feedstuffs to keep them alive and growing. MIG is not a new concept, but it was lost when settlers came to the Americas where land was plentiful. In their rush to expand operations and produce greater quantities, farmers simply clear-cut forests, cropped and grazed the land until it was depleted, and then moved west in search of richer soils to "mine." With the advent of the chemical era, the farmers returned to cropped-out land and simply propped it up with chemical fertilizers, killing all life in the soils. Unfortunately, with the aide of American agri-industry, this course is being repeated in South America at the expense of the invaluable forests of the Amazon River basin.
The positive news is that a small but persistent and growing subset of the farming world is returning to MIG. By focusing on soil and pasture management, not only does MIG produce a better quality food product, but it also is more sustainable, healthier, and more enjoyable. The agri-industry scoffs at MIG stating that it's very management intensiveness means that it won't scale and thus cannot compete globally. However, MIG farmers argue that it is precisely this inherent management intensiveness, and its ability to produce a better life, community, environment, and product, that enables MIG to compete locally. As with many aspects of 21st century civilization, there is an increasing tension between the globalization of capitalist consumerism and the localization of sustainable living.
Three publications that you will find on the kitchen table of many "grass farmers" are:
The Stockman Grass Farmer
Sustainable Agriculture Research and Education