For Release March 30, 1999

Too Early To Burn Pastures

by Chuck Otte, County Extension Agent

Every year, usually in late March or the first of April, I start to get questions about how soon can we burn pastures. "Gosh, you know it’s been awfully warm. Do you suppose we can start burning now?", is the way that most of the conversations start. Every year I have to say the same thing. It’s too early, the average start date for burning is about April 25. I always know what’s going to come next. "If I wait until then it’ll be too green to burn!" And therein lies the problem!

Why do we burn? Tradition? In some cases maybe so. But there are several reasons why we should periodically burn native warm season pastures. First of all fire is a great control for cedar trees and some other brushy species. It won’t control all of our brush and tree problems, but it can sure help keep a lot of them in check. Secondly we burn to improve gains of yearling cattle and to improve grazing distribution. We burn to remove thatch layers of old dead grass thus improving plant growth and reducing the risk of wildfire during the summer.

Are there negative side effects from burning? If it is done right the risks are minimal. When you burn a pasture off you obviously end up with bare soil. If there is a hard rain right after a burn there will be much more water runoff and a risk of soil erosion. With bare soil there will also be an increase in soil water loss due to evaporation. If soil moisture is short or a drought occurs then burning will reduce grass production.

To reduce the negative effects you need to burn at such a time as to minimize the period when the soil will be bare. That means you want to burn when the desirable grasses are starting their new growth. The rule of thumb in the northern Flint Hills is to burn when the Big Bluestem and Indiangrass have 1 to 1.5 inches of new growth. In most years that occurs around the 25th of April. In a warm spring it may be as much as ten days earlier, in a cool year it can be 10 days later. So, depending on the year, you could be burning as early as April 15th or as late as May 5th. But you can not depend on the calendar, you have to learn your pasture grasses and then start checking them.

What happens if you burn too early? The grasses that are just starting to grow at the time of the burn will respond the most favorably to the burn. The grasses that have been growing for some time will be the most seriously hurt and those that haven’t started to grow will be at a competitive disadvantage. In late March and early April the grasses that are really getting growing are cool season grasses. That could be bluegrass, fescue or bromegrass and it could also include many other undesirable grasses.

If you consistently burn two to four weeks too early you will shift the composition from desirable warm season grasses to less desirable grasses. And when you try to burn one of these pastures at the proper time it truly will be too green to carry a good fire. Just as this transition occurred over many years it will take many years to fix it. You will need to start burning as late as possible every year and slowly change the composition back to the desirable grasses.

Remember that fire is a valuable pasture management tool. Make sure you have that burn permit, call in for permission before you burn and then watch it until it’s out. If you started it, you’re responsible for it. The burn permit doesn’t absolve your responsibility. Use fire right and use fire safely!


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