Green Grass: Range managers offer outlookWritten by Jennifer Womack
University of Wyoming Range Scientist Mike Smith has often said, and has the data to prove, there’s a correlation between April soil moisture and forage production. The Roundup caught up with Dr. Smith to ask about his thoughts on how things are looking for grazing season 2009.
“The key to this whole business,” says Smith, “is if the rain or snow comes when the grass is growing or starting to grow, then you get some good out of it. Spring moisture is the key to the whole affair with these cool season grasses that have a Johnnie One Note growth pattern.” That’s good news in areas of Wyoming where ranchers can see tufts of green peaking out from under snowdrifts and submerged in mud puddles.
“Starting in October we have received a continued sequence of moisture from rains to snows,” says Natural Resources Conservation Service District Conservationist Phil Gonzales of Buffalo. “We should expect a good start in grass growth for this year.”
University of Wyoming Cooperative Extension Service (UW-CES) Educator Eric Peterson says it’s a little too early to tell in Sublette County. Snowpack recently climbed to 95 percent of average improving the outlook for irrigators. In terms of rangeland forage production he says late April and early May rains drive lower country production while June and early July rains are the driving influence on higher, Forest Service range.
UW-CES Educator Gene Gade at Sundance says official precipitation readings for the community indicate below average precipitation, but it’s a reading he questions. He says, “We’ve been getting at least one precipitation event each week. We had some recharge of deep soil moisture last fall. Much of the frost went out of the ground a couple of weeks ago, so at least some of the snow melt is infiltrating. Soil moisture is more than adequate to get grass growth started within the next few weeks. If the precipitation remains timely and adequate through May, we should have very good grass and hay production in northeast Wyoming this year.”
So long as there is moisture, the cool season grasses grow like crazy, says Smith. “As soon as the moisture begins fading away they shoot up a seed stalk. As soon as that goes up they start to go dormant. Even though they may stay green, they rarely grow any more. Once they put up a seed stalk any additional growth is a low percentage of total.”
Moisture availability can make a huge difference. “In a really good year in the Laramie area for example,” says Smith, “it might be the third week of June before Needle & Thread puts up a seed stalks. In a really dry year, like 2006, we had seed stalks out in late May. A full three weeks of growth potential is lost because of dry conditions.” It’s a scenario that reduces forage production by half. On the other end of the spectrum, Smith says, “You get good years when it might be twice the average.”
Applying the advice to your own ranch, says Smith, requires remembering the law of averages. “On average the end of April is a really good time to make a decision on what kind of stocking levels you’ll have in the summer,” he explains.
There are exceptions, like 2007. “If you’d done that last year you might have made a mistake.” Cool weather and late May rains delayed production of the cool season grasses, but Smith says clippings on his plots near Saratoga came in above average.
On average, however, Smith contends that late April is a key time for Wyoming ranchers to make management decisions. There’s some variation in timing based on elevation and the mixture of cool and warm season grasses, but April offers a pretty good rule of thumb.
Dates for predicting, he says, open up earlier at lower elevations where the ground thaws sooner. The window for moisture to impact production lasts longer where there’s a higher prevalence of warm season grasses like blue grama. The window for soil moisture to enhance grass production is narrower at Saratoga where there is a greater prevalence of cool season grasses. At Casper, where there are more warm season grasses, it’s longer.
Smith says the Casper scenario should be close to what ranchers in most of northeast Wyoming and the Big Horn Basin can expect. The Saratoga example is a base point for higher elevation locations.
“Nobody who has followed my advice has really gone wrong yet,” laughs Smith adding that in Wyoming he’d have surely heard about it if it happened. “The recent snowfall would tend to suggest that the northeast part of the state and maybe even the Laramie Valley, although I haven’t seen the numbers yet, are shaping up to be pretty good,” says Smith of the areas from which he’s heard reports. “The ground is thawed out so it can soak in.”