Limited rainfall makes grass turnout a difficult choice  

Western Kansas and other regions in the High Plains states have been in drought ratings for months. Prospects for rain aren’t looking good even with the changing weather patterns because of the predicted El Nino later this summer. 

Keith Harmoney, Kansas State University range scientist at the Agricultural Research Center in Hays, discussed choices beef producers have when it comes to turning cattle out on summer pastures during a recent webinar. 

“When we start off with our spring, the way that we have been, folks start thinking about is this going to affect the grazing plans and the grazing strategy that I have in mind or have written down for this coming year?” he said. 

Weather during April to June influences what will be seen at the end of the grazing season. Harmoney stressed how important it is to take a hard look at stocking rates.  

“Why now? Why this time of year?” he said. “I want to show you a link between the precipitation that we receive and our pasture yield at the end of the season.” 

He has what he calls an objective process for making stocking decisions at the start of a season and even as the season starts to carry forward. Harmoney also shared resources that can help ranchers make stocking decisions throughout the year. 

Most producers will make most of their stocking rate decisions long before a single blade of grass has grown. Stocking rate decisions are often based on long-term experience or average forage production in a pasture at the end of the season. 

“But as we all know, we don’t always have average years, and so because of that, we may need to make some decisions on how to change our stocking strategy as the season progresses,” he said.  

Harmoney said producers try to have a balance of 50% take and 50% left at the end of the season. Forage disappearance happens several ways, but it’s usually through grazing, wildlife use, insect use, trampling, weathering, parts of plants blowing in the wind, breaking off, and falling down to the ground as litter.  

“But when we look at the way our spring started, it’s looking like we could have a drought situation on our hands through most of the western part of the state,” he said. “When that happens, and we do have a drought during the season, and we do have less forage production, that means that our balance is out of whack.” 

If stocking rates need to change, then the amount of forage demand changes to maintain balance. Keeping leaves on the plants is important to maintain photosynthesis to keep producing carbohydrates and energy, as carbs are important for root production and growth.  

“One-half to two-thirds of all the dry matter of a grass plant is actually below ground, and that grass plant needs carbohydrates and energy, not only to retain that root system, but also for more roots to grow and replace roots that end up sloughing off and decaying,” Harmoney said. “That leaf material that we need to retain, that 50% is important so that our roots can keep growing, and that we don’t get any stoppage of that root growth, and that we maintain our root biomass.” 

Quality roots help the plant take in nutrients, and in those years where precipitation is lacking, the more root or the more soil volume the roots can explore, the more capable they are of extracting moisture. 

“Maintaining that leaf material above ground and photosynthesizing and keeping those roots growing is very important,” Harmoney said.  

Keeping the 50% residual on top of the ground helps retain moisture. When pastures are heavily stocked, Harmoney said researchers have found that only about 3/4-inch of water was able to infiltrate soils. That’s important in years when there is a lack of rainfall, as rain is likely to come in short, intense periods and not soakers. 

“The better capable our pastures are of being able to allow that water to infiltrate, the more water we’re going to get into the soil, and that water is going to then be directly converted into plant growth,” he said. “We don’t get plant growth if we don’t have water in the soil.” 

Capturing that rain becomes critical and it needs to be captured all throughout the year, but most often that happens in April to June. 

Now, if there’s above average precipitation, there’s often above average production. 

Decision tree

Droughts can be classified as flash droughts, if they come quickly, and Harmoney uses what he calls a decision tree that takes into account the weather data, grazing data and research data he’s collected at Hays from different stocking and grazing studies over time. 

“This decision tree is basically a way to try to make some tough decisions about stocking more objective as you go through a grazing season,” he said. “And really how this grazing or grass turnout decision tree starts is by looking at your pasture or your pasture system, looking at the pastures within it, and looking at how those pastures ended the prior year.” 

Did the pastures have the residual they needed or leaf material during the growing season so they could produce the carbohydrates and store enough energy to make it through the dormant season, allowing enough vigor to start the next year strong?  

“Or maybe those grasses, those pastures were stressed in the prior year. Maybe an area had a grasshopper infestation,” he said. “Or because corn stalks or milo stalks weren’t ready for grazing as soon as you wanted, you had to spend more time out on a couple pastures, or certain pastures, and so those pastures maybe didn’t have the accumulation of carbohydrate that you expected going into the winter.” 

Maybe there was drought damage from a prior year, and it went dormant early—all those factors cause stress on the pasture. 

“In an ideal situation, we would have an unstressed pasture going into the dormant season, and then coming out of the dormant season, those plants should be ready to grow,” he said. “They should kick off in the spring, come right out of the gate, running and be very productive.” 

When it’s the opposite situation; the plants barely made it through the season and dormant season, and the question is will there be enough energy or moisture in the soil for them to start right away. Harmoney said in the 50 years of data researchers have it shows important details. 

“It shows that when we do have moisture during the dormant season stored in the soil to start growth in the early spring, we do expect a little bit higher production from those pastures at the end of the year,” he said. “And so, when we don’t have that spring moisture, we may want to think about delaying turnout or reducing stocking rate a small percentage, just because those grasses may not have the moisture to start that early growth like we expected.” 

Adjustments

Harmoney said if producers need to make some stocking adjustments, they have options. They could early wean and put those calves in a feedlot or ship them where drought isn’t occurring.  

“Early weaning reduces the amount of forage demand by 25% to 35%,” he said. “Those young animals do some grazing, and it does relieve the pressure on the grass from them grazing, but that mostly It relieves the pressure on the grass from the cows.” 

The cows have less forage demand because they’re not producing milk and struggling to maintain body condition. Early weaning also allows early pregnancy testing, and producers can weigh culling decisions. 

“That’d be also a great time to cull some of the worst performers, those that don’t quite match the weaned calf per weight of weaning to cow ratio,” he said. “You may be looking for those with poor structure or poor udders.” 

If this is an opportunity to cull or if you’re having to de-stock, Harmoney said to start with those animals.  

Harmoney also suggested this might be a good time to have a herd of stockers or replacement heifers in the overall cow-calf production system. 

“By having those young animals in your system during years of drought, when you need more forage for your cow-calf pairs, those young animals are in groups that could be de-stocked, and then those acres could be reallocated to your cow-calf herd,” he said. “Having those young animals as a component can help improve the flexibility of your cow-calf herd, and retaining the genetics, if you desire.” 

Rotating out of a pasture all together and putting cows in a dry lot or shipping them to another area can help the range rest and recoup. 

“In the end, establishing an acceptable and sustainable moderate stocking rate is one of the most important management steps that we can do to help maintain the health of our pastures and maintain productivity over a long course of time,” Harmoney said. “But we do know that weather happens, and when that weather happens, conditions change, and so we should have a grazing plan in place based on that moderate stocking rate, but then also plan to make adjustments through the year based on conditions.” 

Kylene Scott can be reached at 620-227-1804 or [email protected].