RANGELAND MANAGEMENT GUIDE SHEET

Daniel A. Nosal, Rangeland Management Specialist

Natural Resources Conservation Service

Telephone: 303-688-3042, ext. 106; Email: daniel.nosal@co.usda.gov

Revised 3/1/06 with assistance from Harvey Sprock, Area Rangeland Mgt. Specialist

INTRODUCTION

• This guide sheet was created to assist landowners (primarily small acreage landowners) in the education and management of their rangeland.
• Productivity of rangeland is limited by climate, soil type, topography, and vegetative species present.
• Succession is the replacement of one plant community by another until a somewhat stable community is reached. This stable community is often referred to as the climax or original plant community. This original condition is generally assumed to have occurred on our rangelands prior to European settlement and is our reference for determining range condition.
• The traditional range condition (similarity index) classes are excellent, good, fair, and poor. Excellent range condition is defined as: 76-100 % of the vegetation is a mixture of desirable plants (grasses, legumes, forbs, and shrubs) in allowable proportions similar to the climax plant community. Good is 51-75 % desirable plants present. Fair is 26-50 % desirable plants, with mostly undesirable forbs and shrubs present. Poor is defined as 0-25 % desirable plants, with invader plants making up the major portion of the vegetation.

CARRYING CAPACITY

• Carrying capacity is defined as the number of animals that a parcel of land can support without overgrazing. It is a function of: type of animal, number of animals, range condition, range site (ecological site), production, and number of acres being grazed.
• The NRCS Technical Guide may be used to determine production based on Animal Unit Months per acre (AUM’s/AC) or acres per Animal Unit Month (AC/AUM). An AUM is the amount of forage necessary to carry one Animal Unit (AU) for one month. An AU is defined as a 1000-pound cow. An average quarter-horse is 1.25 AU’s and a 1400-pound cow is 1.4 AU’s. A range inventory may be conducted to determine range condition. This is somewhat time-consuming and requires training in estimating species composition. Range site may be determined by utilizing the NRCS soil survey.
• A simpler, less time-consuming method is to use average AUM/AC or AC/AUM figures for each range condition class based on the NRCS Technical Guide. These figures assume you have normal annual precipitation. Drought years will need to be adjusted accordingly. The following are average AUM/AC (AC/AUM) figures for each range condition class in Douglas and Elbert counties:

Excellent Good Fair Poor .48 (2.1) .36 (2.8) .24 (4.2) .12 (8.3)

• The majority of properties in this area are in fair condition with lesser amounts of good condition rangeland. If you are unsure of your range condition class, a safe figure to use would be .24 AUM/AC (4.2 AC/AUM) or less if on forested and/or rocky soils. This equates to about 50 acres per animal unit per year.

ANIMAL UNIT EQUIVALENTS (AUE’s)

Cow (1000#) = 1.0 (+.1 for each added 100#)

Cow/Calf Pair = 1.2 (Assuming a 1000# cow)

Bull = 1.8 (Average 1800# bull)

Weaned Calf = .6 - .8

Heifer/Steer (13 - 18 Months or 750 - 900#) = .75 - .9

Heifer/Steer (19 - 24 Months or 900 - 1000#) = .9 – 1.0

Horse = 1.25 (Average quarter-horse)

Ewe = .2

Lamb (12 Months) = .15

Ram = .25

Goat = .2

Bison = 1.0

Other Animals = .1 AU for Each 100# of Body Weight

These figures may be greater if the animals are larger than average.

CARRYING CAPACITY WORKSHEET

Animal Unit Months/Acre (AUM’s/AC From Chart on Reverse Side) = ___________

Acres Grazed = _____________________

AUM’s/AC X Acres Grazed = Total AUM’s (Available or Useable Forage) _______________

Total AUM’s of Forage / 12 Months = Number of AU’s allowed for proper grazing use year-round (carrying capacity)_____________________

AUE’s (From chart above)_________ X Number of Animals_________ = Total AU’s_________

Total AUM’s of Forage _____ / Total AU’s _____ = ______ Number of Months of Grazing/Year

ROTATION GRAZING SYSTEM

• Rotation grazing is defined as a practice in which two or more pastures are alternately rested and grazed in a planned sequence for a period of years. If rotation grazing is not practiced then range condition may not improve, even with proper carrying capacity. Continuous grazing allows the animals to selectively graze, so desirable plants will continue to be overused and undesirable plants will continue to flourish.
• A rotation grazing system should provide for 70-90 days of rest for each pasture following each grazing event or grazing period. Use the following formula to determine the grazing period for each pasture: recovery period desired / number of pastures being rested. This assumes pastures of relatively equal production (AUM’s). If you have different sized pastures, then the grazing period will need to be adjusted accordingly.
• Grazing periods should also be relatively short (10 days or less), but the rest/recovery periods take priority. This may require cross-fencing existing pastures to increase the number of available pastures. Ten or more pastures are recommended to implement a short-duration, high-intensity grazing system (10 days or less per grazing period and 90+ days of rest/recovery following each grazing event) to improve range condition.
• The animals should be rotated as one herd to allow for maximum pasture recovery.