No one knows when or where drought will occur, but this year is shaping up as suspect in several production areas. A warm, dry winter followed, so far, by a warm, dry spring could spell problems for cattlemen and crop farmers alike.

But in areas stricken by drought, cattle in some pastures will find adequate forage through the driest months while cattle in neighboring pastures kick up dust waiting for the rancher to haul in feed. The difference-primarily range management and grazing practices.
In ideal conditions, even poorly managed pastures appear healthy. But when the weather turns dry, the productivity of overgrazed or mismanaged rangeland declines rapidly.

"Water commonly is the most limiting factor for optimized forage production," says range-management consultant Charlie Orchard, of Land EKG, Bozeman Mont. "An old ranch adage says the world's best range management technique won't hold a candle to a few years of extra rain. While there is some credence to that, the simple fact is that waiting for rain to improve your pastures is like waiting for livestock prices to go up to make a profit."

Realistically, he says, drought happens more often than wet years and low prices happen more often than high prices. "There are ranch businesses today that operate profitably during droughts and low prices. So when either factor improves, it is icing on the cake. The key is to optimize the resources that you do have."

Managing the soil surface
Dave Pratt, of Ranch Management Consultants LLC., teaches the Ranching for Profit Schools following the retirement of the schools' founder, Stan Parsons. Mr. Pratt notes that each inch of runoff from a 10-acre pasture translates to 250,000 gallons of water that is not available for plant growth. "It takes about 50 gallons of water to grow one pound of vegetation," he says. "So every inch of runoff potentially decreases that pasture's productivity by 5,000 pounds of forage annually."

Effective precipitation, the amount of moisture that soaks into the soil and makes it down to the roots, is more important than total precipitation. It is less dependent on the amount of rain that falls than it is on how fast the rain falls and whether it penetrates into the soil. The next issue is the soil's water-holding capacity, which helps determine whether that moisture is eventually used by plants or whether it evaporates or percolates out of the root zone.

Organic matter is the key to both infiltration and water-holding capacity, Mr. Pratt says. Litter on the surface helps prevent runoff, erosion and soil capping, which occurs when raindrops strike the soil surface, causing a layer of compaction and washing fine particles into the spaces between larger particles. Capping can occur on nearly all soils and is encouraged by continuous grazing, fire, or anything else that removes vegetation and exposes the soil. Ironically, the impact of hooves of grazing animals usually is the most practical way to break up capped soils.

In terms of contributing organic matter to the soil, surface residue is important but root growth is more so. Roots continuously die off, at a rate of about 50 percent per year, Mr. Orchard says, contributing organic matter directly to soil in the root zone. Vigorous roots help break up soil compaction and create channels through which water can flow.
Grazing the roots
Your cattle, and the way you manage their grazing, can have a positive or profoundly negative impact on water cycling and productivity in your pastures.

Probably the most common cause of poor water cycling in pastures is overgrazing. But, Mr. Orchard notes, many land managers do not fully understand what constitutes overgrazing. The concept, he says, is more a matter of the length of grazing and rest periods than of how much forage animals consume from a pasture.

After a plant is subjected to grazing, short-term regrowth can draw on energy reserves in the root system, he explains. If the plant is grazed again, before the root system recovers, regrowth will be delayed or the plant could die. "The development of roots is directly related to the rancher's treatment of the tops of the plants," he says. "Continuous grazing reduces root volume and causes reduced soil porosity and infiltration."

Mr. Pratt explains that when animals eat 10 percent of a plant's foliage, it has no impact on root growth, and the impact remains minimal as animals eat more, with root growth cut by only 3 percent with half of the foliage eaten. At 60 percent consumption though, root growth is cut by half. And if animals eat 80 percent of the plant's foliage, root growth stops completely for 12 days. The percentages might vary depending on the plant species, but the trend is consistent. There is a distinct threshold level where grazing affects root growth.

These figures do not mean that ranchers never should allow their cattle to graze more than half of the forage in a pasture, Mr. Pratt points out. Instead, they help illustrate the importance of recovery time to rangeland health.
"The rest period is critical," Mr. Pratt says, especially on dry Western rangeland. "You need to avoid returning cattle to a pasture before plants have recovered from the previous grazing cycle. The grazing period needs to be short-keep animals from taking that second bite from plants that have started to recover." Ranchers, he says, need to stop grazing their roots.

With these concepts in mind, Mr. Pratt and Mr. Orchard advocate grazing systems described as cell grazing, pulsed grazing or management-intensive grazing. These methods involve short grazing and adequate rest periods, high stock densities and stocking rates that reflect changes in carrying capacity.

"Short-term animal impact using concentrated hoof action, can be very positive in terms of water cycling in pastures," Mr. Pratt says. Frequent moves to fresh feed produce a "herd effect" in which cattle move around excitedly, with their hooves breaking up crusting or compaction on the soil surface. Their activity mixes surface organic matter into the soil and creates germination sites for seeds. The rest period between each grazing cycle allows recovery of roots and foliage, increasing the deposition of organic matter both above and below the soil surface.

Optimum timing for grazing and rest cycles varies depending on location and time of year, but the key point is to keep grazing periods short and rest periods long enough for recovery. "Animal impact is a powerful tool," Mr. Pratt says, "and timing is important." He uses an analogyof a crop farmer with a plow. Used properly, the plow is a useful and powerful tool. But year-around plowing clearly would be counter-productive.