Range and Pasture Management when Dealing with Drought

Introduction

Every farm or ranch has poor production at times within a year or for a year or longer due to drought. One of the risks to be managed for in advance and during farming or ranching is based on whether drought occurs often or quite infrequently. Good range and pasture management will minimize the effects of drought when it occurs. A lack of available forage would indicate that the range and pasture management practices should be reviewed in relation to stocking rates and the amount of litter or forage residue maintained. Regardless of how a drought is defined, dealing with it is serious business. If drought is not planned for or managed in ways to reduce long term effects, a beef operation will become unprofitable or fail. To successfully manage in the face of drought, a producer needs to know how drought will affect plants, livestock, and management practices.

Perennial Pasture

The management of a perennial pasture, both native range and tame pasture, is different than that of annuals. Perennial pasture offers some protection against the variation in production of annual plants.

Past grazing practices have a large bearing on what happens to a perennial pasture during a drought. To better realize what our climates impact on pastures have it is important to think about how native forage species naturally evolved under mother nature's grazing practices. Native range plant species evolved to best handle grazing systems of fire or nomadic herds of bison. These often severely removed forage growth from the landscape but as the fuel for future fires was not present or as the buffalo moved on there was long periods of time for recovery with no grazing. Plants were naturally allowed time to regrow or even set seed from these natural grazing incidents and as a result maintain their vigorour nature. In our present grazing system pastures that are not overgrazed (regrazed before plants have had time to recover from a previous grazing or in spring after winter plant food store use) develop a deeper rooted, vigorous forage plants. Overgrazing coupled with severe removal of top growth develops plants with shallow root systems and there is a loss of more productive plant species to less productive, grazing resistent plants. Forage production dramatically decreases during a drought, and the shallow rooted plants present are affected sooner and to a greater degree than the more deeply rooted ones. A highly vigorous deep-rooted plant will be less dependent on frequent precipitation than a shallow-rooted plant.

If pastures are not grazed for short periods of time, and not left without grazing to allow plant recovery, light or moderate use is another less damaging grazing alternative. Moderate use of top growth offsets some effects of overgrazing and is indicated by the amount of carry over or litter left at the end of the grazing season. Rules of thumb indicate leaving approximately 50 per cent of the current growth for native range and approximately 30 per cent of the current growth for tame pastures. This permits a conservative use under a well managed, continuous grazing system. Research has shown that litter reduces the soil surface temperature and therefore reduces evaporation. Although litter is low in nutrients and has low palatability, it can be used by livestock when forage is limited. The green forage growing through the litter will raise the nutrient level of the litter and make it more acceptable to cattle. A deliberate decision has to be made about maintaining the litter level in a pasture and in what pastures more needs to be or can even be created. Some productive tame forage species( for eg. orchard grass, meadow bromegrass or alfalfa) are naturally very low litter producers even in well managed vigorous grazing systems. Other tame or native pastures can be managed for higher litter levels. One these latter pastures are the cows worth enough to justify reducing pasture litter? Is the pasture condition more important for its drought proofing capabilities in the future? If litter in perennial pasture is not maintained, it becomes more dependant on frequent precipitation during the growing season, as is the case in annual crops. For this reason, forage yields become less predictable on a yearly basis and the carrying capacity of the range or pasture more uncertain.

A perennial pasture in optimum condition ensures the most cost-effective forage production and stable within year and from year to year. This in turn will reduce pasture-animal carrying capacity changes from year to year.

In summary, a proper stocking rate should be monitored and matched to forage production (reduced in a drought), from deep-rooted vigorous plants, and sufficient carryover or litter left at the end of each grazing season, will reduce risk or long term setback to ranching operations.

Annual Pasture and Emergencies

Rather than overgrazing or decreasing the amount of litter in a perennial range or pasture, an escape mechanism with annuals should be planned. In many areas, oats into previous crop standing stubble is the annual cereal to consider. Depending on the need, oats may be grazed, cut for silage or harvested as either greenfeed or grain. Barley, fall rye, winter wheat, or triticale may be substituted or used in conjunction with oats in intensive annual pasture operations each having their different advantages and disadvantages.

If moisture is adequate, the annual production with annual forage plants may be as much as four times that of native range or two times tame perennial forage production. Annuals may be used on a regular basis for pasture where land area is limited. Oats seeded at two to three bushels per acre will provide enough pasture to feed a cow for about 100 days, (with a 4000 pound yield) with grazing starting at six weeks after seeding. This, then, may be grazed or harvested depending on needs. Annuals may provide grazing for a herd of cattle for approximately 100 to 120 days each year, if the ranch management can survive the annual variation in forage production and the added expense of seeding each year. Yields of annual pastures are higher when forage is grazed to about a 3 inch residual, once this occurs animals are pulled and returned once regrowth has reached 6-8 inchs. Annual forage production is totally at the mercy of precipitation and soil moisture each year. Forage production may be zero if there is little rain.

Complementary use of perennial and annual pastures can alleviate short term drought conditions. For example, spring-seeded annuals can be grazed during July while perennial pastures are rested.

If cereals are not normally grown, cattle can graze hay fields or winter pastures as long as stock water is available.

Cattle

Unless stocking pressures are reduced in accordance with forage production, weaning weights may be seriously reduced. Research has shown that suprisingly normal or greater weaning weights can be achieved when stocking pressure is adjusted to the limited forage supply in a drought. Cow body condition is more impacted than calf performance. If cow body condition score falls to 2.0, the cow's ability to breed on time will usually be impaired.

When cows do not get adequate nutrition, either before or after calving, they respond by missing one or more heat periods or remain open throughout the season. This affects profit from future calf crops as the length of the calving period from delayed breeding, placing second calf heifers and thinner cow's calving well after the rest of the herd.

In planning for drought, it is wise to develop and follow certain steps which will minimize the effect on both pasture and livestock. The first priority is to have a flexible breeding herd. This means maintaining only two-thirds to three-quarters of the herd as a cow-calf operation and carrying the remainder as yearlings for replacements.

Yearlings become expendable when adjusting for drought. Depending on the conditions expected, one-quarter to one-third of the herd may be grazed, sold or put into the feedlot. When drought is expected, the next step would be to cull the cow herd heavily.

These steps, if followed when planning for drought, will minimize the effect on both the pasture and the livestock:

• Match the projected pasture production in Animal Days Grazing (40# forage/cow/day) to the animal number and length of grazing season desired.
• If this does not match up, now is the time to do something about it.
• Be further prepared to balance the stocking rate to the amount of forage present on a regular basis throughout the season.
• Have a flexible breeding herd.
• Cull heavily the older cows, cows with physical defects, open cows, cows that have difficult births.
• Wean early.
• Pregnancy test.
• Monitor bull condition throughout breeding season.
• Monitor bull and cow rations.