Will the rains come?

KIMBALL, Neb. – Time to dust off the grazing plan.

When it comes to grassland forage production and livestock grazing, here in the tri-state region we’ve been quite fortunate over the last half-decade. Since the last real drought of 2012, most locations across northeast Colorado, southeast Wyoming, and the Nebraska Panhandle have seen timely and adequate precipitation. With enough moisture in the soil, mother nature has produced abundant grass and our cattle have grown fat across five years of long, worry-free grazing seasons. Most of us know, however, that abundant grass production is anything but guaranteed across the region. Will the rains come in 2018? And if not, what will we do?

Expending the time and effort required to put together a grazing plan – or to reexamine an existing plan – can be an extremely valuable exercise. A grazing plan can answer the “what to do” questions and provide us with target dates and a decision tree for guidance. Planning allows us time to think about and study options before a crisis – such as drought – arrives. Moreover, systematized planning will allow us the opportunity to husband and improve our grassland resource in the long term.

In taking a systematized approach to grazing management it’s helpful to think about the ranching system as a whole where the grassland ecosystem is the main production resource. If you think about it, this is in fact the case. Our pastures and rangeland exist in a particular geographic location which features a particular climate. Nature provides the soil, grass, water, and sunshine. The annual combination of these things determines the actual productive growth of the grass, and we employ cattle to harvest the grass and turn it into a saleable product. We have no control over nature, which leaves only the harvesting aspect to manage; when to graze, and how much to graze.

That’s the management question then. When, and how much to take. To arrive at the proper answer, one that supports the long-term health of the grass asset and allows us a modicum of profit, we need to understand the grassland ecosystem we’re managing.

In this part of the world we exist in a semi-arid climatic zone, characterized by annual precipitation of between 10 and 20 inches and an overnight temperature fall-off during the growing season. There is also a dynamic year-to-year variation in the timing and quantity of precipitation.

Rangeland is a discreet ecosystem, easily as complex as the most pristine rainforest. Rangeland grasses are unique in the plant world in that their root systems are more extensive than their above ground herbage. In shortgrass rangeland root systems can be five or more feet deep; some tallgrass stands root to a depth of better than 30 feet.

These extensive root systems allow grasses to find and use water and nutrients throughout the soil profile, which helps them survive in dry years and explode with herbage production in wet years. They also anchor soils and provide a rich environment where symbiotic microorganisms thrive and boost soil fertility. Many rangeland grasses reproduce through their root systems as well, pushing rhizomatous stems out beneath the soil from which new plants arise.

Here on the Wyo-Braska High Plains, native and reintroduced rangeland grass species include cool and warm season grasses and grass-like plants (sedges). Native range is shortgrass prairie, and reintroduced grasslands shortgrass species with a scattering of mid-height grasses.

Sedges are usually the first to green up in the spring, followed by cool-season and then warm-season grasses. There is considerable variation between species and even within species according to location, but most grass growth occurs during 30-60-day rapid growth periods corresponding to the onset of particular air temperatures. In general, maximum growth in cool-season grasses occurs when air temperatures are 65 to 75 degrees, while max growth of warm-season grasses occurs with 90-95-degree air temps.

Such growth characteristics allow range grasses to produce the bulk of their above ground herbage during a relatively short period each year. The staggered peak growth periods between types and species generally provide a three- to four-month annual period of lush, palatable and preferred forage for selective grazers, likely as a result of rangeland ecosystem evolution. Peak growth occurs relatively early in the season, and once past this heavy herbage production period, above ground growth slows markedly, with the plants essentially in maintenance mode until hard freeze.

Herbage production and plant growth during peak growth is highly correlated to soil moisture and air temperature. Both are required. Under severe drought conditions grass may remain essentially dormant. If moisture is available, however, peak growth will occur when air temperatures are appropriate and will be limited by moisture availability. In wet years herbage production will be abundant, in dry years production will be sparse.

Aside from herbage production, which is so essential as forage to livestock producers, root growth and development is at its highest level during peak growth. With root systems making up the bulk of grass plants, root development is obviously vital to the range ecosystem. Carbohydrates derived from photosynthesis provide the plant with the energy needed for both above and below ground growth. When carbohydrate production is reduced by grazing, the plant diverts energy from root development to herbage production in an effort to maintain photosynthetic carbohydrate production. This shift from below to above ground growth has been called root mining. Depending on factors like grazing pressure, soil moisture, and air temperature, root mining can be detrimental to the long and short term health of the plant, and by extension, the range ecosystem. Heavy grazing during drought can debilitate an entire pasture, which may take years to recover. Even modest grazing during peak growth results in some level of root mining. The operator’s challenge is to understand his rangeland and livestock as a discrete system and introduce management practices which enhance both profitability and sustainability.

In general, most recommended range management schemes include dividing range into a number of pastures and rotating grazing dates and periods between them from year to year. In a four-year rotation, a particular pasture might be heavily grazed during peak growth one year, rested the next year, then lightly and moderately grazed in the next two years.

Range management plans will necessarily be different for different operations. No two rangeland parcels are alike, weather varies from year to year, and grazing requirements change according to economic and other variables. Designing and implementing a range management plan can be a complex and daunting task, but armed with knowledge and experience, operators can employ powerful strategies to maximize both profitability and sustainability.

Next week we’ll look at some of the nuts and bolts of a grazing plan.


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