Thursday, January 1, 2015

Grazing during Dormancy

In the last week, our weather in the Sierra foothills has turned cold - finally!  While I welcome the onset of winter (especially after the 11+ inches of rain we had in December), the cold weather and shorter days mean that our annual grasses have gone into their winter dormancy.  And with dormancy comes a change in our grazing strategy.

We are always concerned with providing adequate rest for our pasture grasses to regrow after a bout of grazing.  On our un-irrigated rangelands, this rest phase varies from 20-25 days (in March and early April) to 45-60 days (after fall germination and before winter dormancy).  Our annual grasses have two dormant periods - summer (after the grasses die and before a germinating fall rain), and winter (once the soil temperatures and day lengths drop past the critical point).  Now that our rangelands have gone into winter dormancy, they won't start growing again until the soil temperatures and day lengths cross back over this threshhold - usually sometime in mid-February.

All of this means that the paddocks we're grazing today (January 1) won't be grazable again for at least 30 days after growth resumes (we'll probably pass through these paddocks again in mid-March).  In other words, we won't get any significant quantity of new forage for about 75 days.  What grass we have now will have to carry the ewes through until then.

With more than 17 inches of rainfall since the rain "year" began on July 1, we're much better off this January than we were last year.  When I look back at photographs from last January, I'm amazed by the lack of green!  The other difference, however, is the lack of standing dry forage this January.  With all of the rain we've had, last year's grass crop has largely decomposed.  Last year, the standing dry grass saved us - we were able to feed supplemental protein and meet our ewes' fiber requirements with dry forage.  This year, we'll need to stretch the standing green forage that we have on January 1 until the grass starts growing again.  Every year is different; the art of managing rangelands and livestock requires us to stay flexible!  Happy 2015!

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