by Dr. Jeff Mosley, Professor of Range Science and Extension Range Management Specialist, Department of Animal and Range Sciences, Montana State University—Bozeman


"Most seeded pastures, especially sub-irrigated or irrigated ones, can tolerate heavy grazing..."

Here it is spring and we’re still waiting for winter moisture. Like everyone else, I’m hoping and praying for a wet spring and summer with timely rains that will somehow carry us through another year. Until the rains arrive, I know many people are making contingency plans for early weaning, just in case. It’s also a good time to be thinking about how to use seeded pastures this spring and early summer. Most seeded pastures, especially sub-irrigated or irrigated ones, can tolerate heavy grazing — more so than native rangeland. Therefore, when grass is in short supply, it makes sense to allocate more of the grazing load to seeded pastures. The more time you can allow for native rangeland pastures to grow this spring before they are grazed, the better it will be for the long-term health of your range and your ranch business.

Are your seeded pastures fenced separately?

Seeded pastures should be fenced separately from native rangeland. Also, seedings of different species or mixtures of seeded pastures should be fenced separately from each other. This is advisable because of the differences in growth rates, palatability and grazing tolerance among plant species. Separate pastures enable you to use the plants when they are the most palatable and nutritious, or when their use best complements your other forage sources. Maybe this spring it’s time to consider using temporary electric fence to separate some isolated parcels of seeded grass in order to make better use of them.

How soon to begin grazing this spring?

Plant height is a good indicator of when a seeded pasture is ready for grazing. Most species that are commonly seeded for dryland pasture in Montana are ready for grazing when plants are 6 to 8 inches high, and grazing should cease when 3 to 4 inches of stubble remains. Crested wheatgrass or Russian wildrye pastures are ready to graze four to five weeks earlier than native rangeland.Livestock will perform better if grazing is delayed until the amount of forage standing in the pasture (new growth plus any carryover grass still standing from previous years) reaches 200 to 300 lbs/acre. Another guideline is to delay grazing at least until individual plants have grown three leaves and each of these leaves have reached at least 2-1/2 inches in length. These guidelines also will help reduce the incidence of grass tetany (see related article, p. 3).

What is a reasonable stocking rate?

In the 10 to 14-inch annual precipitation zone, 0.5 to 0.7 AUM/acre (1.4 to 2.0 acres/AUM) are good ballpark figures. For pastures in the 15 to 18-inch zone, consider stocking rates of 1.0 to 1.25 AUM/acre (0.8 to 1.0 acres/AUM).

Is rotational grazing necessary for seeded pastures in spring?
Seeded pastures that are only grazed in spring for brief periods (i.e., three weeks or less) do not benefit much from rotational grazing. If more grazing time is needed in spring, it is a good idea to divide a seeded pasture into two or three smaller ones so that each pasture is not grazed for more than three consecutive weeks. Also, dryland pastures in spring usually need about a three-week minimum recovery period before they can be regrazed.

What if it doesn’t rain?

My dad has always been fond of reminding me that “you can’t get blood out of a turnip.” Once again, Dad’s wisdom rings true — ‘nuff said. But as you keep your eye on the rain gauge and your grass supply this spring and summer, remember that by July 1, your rangeland will have produced about 90 percent of its forage growth for Spring/Summer 2005. Any rains that come after July 1 will help stream flow and groundwater recharge, but that moisture will have little effect on forage growth. Here’s hoping for some plentiful and timely moisture, but it just makes good sense to have a back-up plan that you
can put into motion, if necessary, in early July.

This information is for educational purposes only. Reference to commercial products or trade names does not imply discrimination or endorsement by the Montana State University Extension Service.