Grass website offers tools for livestock producers

The question is on the top of ranchers’ minds right now; how much grass will we have this summer? Overall, it was dry last fall, over the winter and so far, this spring. How much grass will there be this summer? Directly related to that question, how many head of livestock can I graze this year. How long can they graze?

Oh, for a crystal ball. Since one is not likely to drop out of the sky, we can use the next best thing: grass cast.

Grass-Cast or Grassland Productivity Forecast, has over 30 years of historical data about weather and vegetation growth. It compares that data with current year precipitation to create three production forecast maps. Each map indicates the expected grass growth based on above-normal, near-normal or below-normal rain. Grass growth is color coded from 30 percent above to 30 percent below normal. In the past, these predictions were county based. However, this year a user can zoom to six-mile by six-mile areas.

The first maps are released in early April and are highly speculative. However, as time goes by and actual rainfall is recorded, the biweekly maps become more accurate and useful. Particularly when paired with what is known about the timing of grass growth.

Extension research across the plains has found that grass growth is best predicted by precipitation received 30 days prior to the peak growth period. There is a point when the grass hits peak leaf growth and shifts to making seed and food storage for the winter. This shift occurs somewhere between June 15 and July 15. The 30-day period prior would therefore be May 15 to June 15.

Using this knowledge in conjunction with Grass Cast maps is a powerful planning tool for grazers. Instead of being trapped in a bad situation, the livestock operator is now in the driver’s seat. Small changes to a livestock operation starting in May or June amplifies the August outcome. Strategic destocking, locating other feed and early weaning can significantly reduce the financial and emotional stress of late summer. Acting early also reduces the risk of over grazing pastures, which only leads to reduced production in the following years.

In just its second year, the Grass-Cast website was visited nearly 3,000 times by over 1,800 different users. The website is https://grasscast.unl.edu/.

Grass Cast was developed in 2018 by United States Department of Agricultural Research Service. Other partners include the Natural Resources Conservation Service, Colorado State University, University of Arizona and the National Drought Mitigation Center at the University of Nebraska-Lincoln.