SUSTAINING AND ENHANCING SOUTHERN PLAINS RANGELAND AND PASTURE LANDSCAPES
Location: Rangeland and Pasture Research
Title: Drought and rangelands.
Submitted to: Cattleman's Magazine
Publication Type: Trade Journal
Publication Acceptance Date: January 21, 2012
Publication Date: February 1, 2012
Citation: Gunter, S.A., Springer, T.L. 2012. Drought and rangelands. Oklahoma Cowman 51(2):34-35.
Droughts are common and occur regularly in Oklahoma. They’re the most costly natural hazard to the United States, and estimates show a $6-$8 billion annual loss to the nation’s farmers and rancher. With the current drought impacting Oklahoma, people managing rangelands are concerned with the short- and long-term effects to rangeland plants. Rangeland plants have adapted to an environment with frequent droughts; hence, rangelands should recover nicely with appropriate management.
To understand what will happen in the future, we can look to droughts of the past. In the 1950’s, Oklahoma experienced a drought similar to the drought currently under way. During that previous drought, scientists with the USDA’s Agricultural Research Service at Woodward monitored the changes that occurred to rangelands and how they recovered.
From 1953 through 1956, northwest Oklahoma received approximately 69% of its normal precipitation. For this drought, the number of perennial grass plants per acre decreased by more than 50%. This decrease was especially noticeable with the tall grasses, like sand bluestem and little bluestem. Also, stocker cattle (9 acres/steer) and cows (17 acres/pair) stocked at moderate rates during the drought were more profitable than cattle stocked at heavier rates (6 acres/steer, 12 acres/pair). This profitability resulted from greater individual gains or weaning weight and reduced fixed costs per animal.
Once the drought ended, with a more normal precipitation patterns starting in 1957, total forage production quickly recovered. In 1958, when pastures were re-evaluated for grass and forb biomass, the pastures were quite weedy with annual forbs. Also in 1958, the short grasses, like blue grama and buffalograss, had quickly recovered.
But it wasn’t until 1961 that grass composition had returned to near pre-drought conditions in pastures with a moderate stocking rate. The exception to this generalization was sand bluestem, which recovered to about half its frequency as before the drought, but it was increasing.
During this recovery period, pastures that had been heavily grazed had considerably more erosion as raindrops from storms struck the bare, sandy soils and resulted in large amounts of soil being washed into the swales, smothering the best grasses, adding to recovery time. The erosion on the moderately grazed pastures was much less and the grass recovered quickly.
Because of the increase in annual forbs in pastures after replenishing rains, some managers are tempted to spray with broad-leaf weed killers. Present day studies, however, have shown that annual forb production will decrease as ground cover from perennial grasses and forbs increases and suppresses these annual plants.
During a drought on native mixed-grass rangelands, it is important to keep stocking rates at the moderate to light intensity. More conservative stocking will maintain ground cover and enhance plant vigor. Research from the ARS Southern Plains Range Research Station in Woodward has shown that moderate stocking during droughts makes the cattle enterprises more profitable. Once the drought ends and the pasture enters recovery, moderate stocking rates will allow perennial grasses to recover more quickly and compete with undesirable grass and weeds that will attempt to invade if pastures are overgrazed.