The Globe outdoors columnist

May 15 is the deadline for spring burning to enhance wildlife habitat.  This most often takes place on private lands enrolled in CRP.

CRP stands for Conservation Reserve Program.  It is a federal farm program that pays landowners to idle marginal lands to provide clean water benefits and wildlife habitat. The CRP contract is 10-15 years and pays a per-acre rental rate.

The idled acres are planted to perennial grasses and flowers. There are currently approximately 25 million acres across the United States enrolled in the program. Most of the acres in southwest Minnesota are small parcels located in filled corners or other hard to farm locations. Other common spots are along stream courses to keep the soil from entering the streams during rain events.

As part of the program land owners are required to complete mid-contract management.  This is mowing or burning one time in about the middle of the contract term. The activities stimulate the grasses and keep the stand more energized. Burning does the best job of the two choices.

The big question is: Why is this burning done in the spring when pheasants, ducks and other ground nesting birds are already nesting?

It’s a great question that I have answered many times, but it still is being asked to me several times per week.

As the grass stands mature, they start to be encroached by grass species that are undesirable. The most common culprit is non-native smooth broghm. It is a cool season grass and it is one of the first grasses to green up in the spring.

The CRP stands are planted to warm season grasses and don’t start growing until after June 1st on average.

The smooth broghm gets a big head start each spring, and if left uncontrolled will soon out-compete the desirable grass species. If let unmanaged, most stands of CRP grass will be completely converted to cool season broghm in about 7-8 years.

This invasive grass does little for wildlife.  After the first snow of the winter it will lay as flat as the rug on your front step. Warm season grasses, on the other hand, will stand firm all winter long and provide cover for many different species of wildlife.

The goal of mid-contact management is to benefit the warm season grasses and deter the undesirable cool season broghm.

Burning in the spring after the cool season grasses have emerged actually sets those undesirable grass back. As a result of the fire, the ground is black and then heats up very quickly. As the soil temperatures rise the native warm season grasses get a big jump-start. In many cases the warm season grasses will see a growing season that is 45 days longer than in years where no burn takes place.

The undesirable grasses are injured and the desirable grasses get a kick in the butt. As a result, the habitat is greatly improved. There will be a few nests that are destroyed as a result of the fire, and those birds will re-nest in a different location.  

This is why you normally only burn one-third to one-half of the spot in any one season. This gives the re-nesting birds an alternative place to go.

Burning native grass stands is best done on about a 4-5 year rotation. May 15 is the deadline for burning federal contract acres in an effort to limit nesting losses.  Private lands not in a program can be burned any time, but all of the folks I know also try to adhere to the 15th deadline.

Burning provides many other benefits.  If can kill most of the small volunteer trees that try to make a foothold in your grass stands.  They also reduce other invasive plants that cannot tolerate a fire. If the trees and other shrub plants are left unattended, that can grow to a size that requires a chain saw instead of a match to be removed and this is a much more expensive method to utilize.

Utilizing fire also exposes other hazards that can then be removed for the benefit of both animals and humans. Barbed wire, chunks of steel and other debris are common hazards found after a burn.

Burning is a vital tool for habitat management. When it comes to bird nest losses, just remember -- the short-term pain is far outweighted by the long-term habitat gains.