Farm Talk

September 11, 2012

Letting the research do the teaching

by Doug Toburen

Parsons, Kansas — When Willie J. Bressner donated over 600 acres of land in Woodson County, Kansas, to the K-State Foundation, it was donated without restrictions. However, Mr. Bressner requested that it be utilized as an experimental project to study the preservation and use of native grasses.

So, since 1988 that is exactly what K-State Research and Extension agents have been focusing on—preservation and use of native grasses.

“This is cattle country and we want to keep it cattle country,” said Cade Rensink, former K-State Extension agent at the recent Bressner Pasture Field Day.

In order to do that, those in charge of the K-State Bressner Range Research Unit in Woodson County decided to embark on a seven-year journey and research the effect of patch-burning on the tallgrass prairie.

According to Rensink, the pasture was divided into 8 small pastures where one-third of pastures 1-4 were burned each year and pastures 5-8 were completely burned each year.

The idea behind the research was to evaluate livestock performance and examine forage utilization and grazing distribution, among other things.

Rensink went on to explain that burning occurred in April prior to stocking with 550-lb. animals from mid-April to mid-August using a 114-day grazing system allowing 2.7 acres/head.

“Although the research unit is owned and operated by K-State, the pastures were leased and stocked by private ranchers,” Rensink explained.

The pastures, according to Rensink, were made up of the big five grasses — big bluestem, little bluestem, indiangrass, switchgrass and sideoats grama.

Annual grasses, including crabgrass, yellow bristlegrass and common witchgrass, made up less than 10 percent of the botanical composition, except for 2009, a year following a wet summer.

Although very labor intensive, researchers did come up with some very interesting and useful information.

“After two patch-burn cycles, botanical composition shifts were similar on patch-burn pastures and full-burn pastures,” Rensink explained. “One major change was the increasing number of forbs on the patch-burn units.”

According to him, sericea lespedeza was increasing in most pastures. The full-burn pastures were sprayed for sericea lespedeza.

According to the research, the most dramatic change in botanical composition was the increase in annual grasses the year of patch-burning. These species declined in the two years following the patch-burning. Big bluestem, sideoats grama, and forbs remained relatively stable during the patch-burn cycles. Little bluestem and indiangrass recovered following the first burn. Switchgrass composition has trended downward following patch-burn.

In summary, Rensink and K-State Associate Professor of Agronomy-Range Management, Walter Fick determined several things.

1. Forbs were tending to increase under patch-burning compared to full-burn pastures.

2. Sericea lespedeza was increasing regardless of burning regime.

3. Annual grasses, including common witchgrass, yellow bristlegrass, crabgrass and prairie threeawn, dramatically

increase the year of a patch-burn.

4. The native grasses monitored, except possibly switchgrass, remain stable or recover the two years following patch-burn.

“There has been a lot of learning throughout this research,” Rensink explained. “This is a form of science that we have seen some renewed interest in and it seems to work.”

In addition to maximizing plants Rensink said the research done also aided in increasing wildlife.

“In the end, it doesn’t really matter what you think of it, you are going to learn something,” Fick concluded.

In addition to forage composition,

cattle performance was measured from grazing on full-burned versus patch-burned pastures.

According to David Kehler, K-State

Butler County agriculture agent, the greatest cattle gains were achieved in 2009 and 2010, with the lowest cattle gains in 2007 and 2012.

Kehler explained that there was no significant difference in average daily gain between full-burn and patch-burn treatments with a least significant difference of 0.10 lb/head/day.

“Cattle grazing on the patch-burn pastures gained 2.44 lb/head/day during the research while cattle on the full-burn pastures gained 2.42 lb/head/ day,” Kehler said.

The research concluded that, similarly, the season-long cattle gains per acre were not significantly different across years.

“The average gain per acre for the patch-burn and full-burn pastures were 118 and 116 lb./acre,” he concluded.£