Thursday, October 23, 2014

Managing Drought Risk on the Ranch

Grazing Response Index

*excerpted from "Understanding Rangeland Monitoring" by Scott Cotton

The Grazing Response Index a general matrix guideline designed to help land managers determine how and when to graze pasture. This matrix was devised by combining the natural growth patterns of grass, its ability to recover within certain periods of time and the difference in grass recovery caused by stocking intensity.

This grid lets managers evaluate the frequency they have grazed pastures, the intensity with which they have grazed pastures and the opportunity the pasture has had to rest and recover. By assigning scores to these three considerations, a manager can determine which pasture to use next and have some indication of the intensity to use.

Grazing Response Index

Frequency of Use

Intensity of Use

Opportunity for Rest

Less than 2 Uses

(+1 score)

Light Use

(+1 score)

No Rest

(-2 score)

2 Uses

(0 score)

Moderate Use

(0 score)

Some Rest

(0 score)

3 or More Uses

(-3 score)

Heavy Use

(-1 score)

Long Rest

(+2 score)

Here is how it works. A manager must determine how he/she has used the
pastures in recent and past periods. Then you score each pasture. Determining
frequency, intensity and rest may require a little technical help at first but it’s
usually fairly intuitive. Then you compare the score of all your grazing site
alternatives.

THE HIGHEST SCORE SHOULD BE YOUR NEXT GRAZING LOCATION!!!

Example of GRI

PASTURE A
Currently in this pasture
so it is not scored until
you move out.

PASTURE B
Used once this season,
moderately, with partial
season of rest. Score +1

PASTURE C
Used 3 times last year,
heavily with a full season
of rest. Score 0

PASTURE D
Used once early this
season, heavily but had
partial season rest.
Score 0

PASTURE E
Used twice this season,
moderately, little rest.
Score -2

PASTURE F
Used none this year, last
use moderate, season
long rest. Score +2

These considerations will become automatic after awhile, the grid just helps to form the evaluation. Obviously a manager would want to move to Pasture F next and then probably Pasture B.

Please notice that the amount of rest and recovery a pasture receives, gets weighted much more heavily than frequency of use, or intensity of use.

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