For Release February 18, 2003

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

Northern Flint Hills pastures are in dire need of some serious management adjustments for the next several years. The most important adjustment is going to be stocking rates. There are several factors at work here. Let’s look at each one in detail.

First and foremost is the weather. The pastures have been damaged by three years of drought. While the native grasses can handle drought, they do so by reducing crown size, root mass and ultimately top growth. Following the three bad years that we’ve had, it isn’t unreasonable to think that our pasture grasses could be producing one half what they were five years ago. A grass plant can not recover from three years of stress in one year. It will take at least two, if not three normal years to undo the damage done.

Secondly, many pastures have been overstocked for many years. In pasture management we discuss animal unit months or AUMs. One AUM is the amount of forage that a 1,000 pound cow will eat in one month. One AUM is 750 pounds of air dry forage. Most of our pastures, in good condition, will produce from 0.60 to 1.10 AUMs depending on if it is a rocky break, a shallow soil or a better side hill or top of the hill pasture.

Let’s take that math a little further. Let’s say you have a 1,000 pound cow who is going to wean a 400 pound calf . You intend to pasture them for the full six month pasture season. The cow will need 6 AUM for herself. A 400 pound calf will need about 0.3 AUM per month or 1.8 for the entire season. Add those together and the pair will need 7.8 AUM for the entire season. Even if the entire pasture averages 1 AUM per acre, which is about average in a normal year, that means that the pair needs 7.8 acres to meet their nutritional requirements without damaging the grass from overgrazing. Last year’s bluestem pasture rental survey showed that on the average, landowners were guaranteeing 7.4 acres per pair. Even before drought stress, we were overgrazing.

Let’s go a step further and look at the cow calf herds that many producers have today. Let’s take a 1,200 pound cow with a 400 pound calf. Their requirements will be 9 AUM for the season. If that 1,200 pound cow is weaning a 500 pound calf, then this will raise the requirement to 9.6 AUM. Can you see now why the pastures are starting to look the way they do? Realistically, we need to be planning on around 9 acres per cow calf pair IF the pastures are under normal conditions.

What about this year? It all depends on the rainfall from here on out. We are slightly above normal rainfall since October 1st. If that trend continues, then we still need to reduce stocking rates about 40%. Or start planning on 12.5 to 13 acres of good grass per pair. If the spring turns off dry, then you can up that to 14 to 15 acres per pair.

You also need to seriously evaluate your pasture for overall condition and acres of usable grass. If you have a pool table top bare pasture right now, then additional reductions may be necessary. If you have a 240 acre pasture and 60 acres is brush and trees, make sure you are calculating your stocking rate based on 180 acres of usable grass.

Flint Hills pastures are not a resource that can be mined. You can’t stock ‘em nose to tail for a few years and then move on. These pastures need to be treated with care and looked at as a renewable resource. You have to take care of the grass factory and leave enough of the factory so that more grass can be produced for next year!

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