Tuesday, March 10, 2015

Different Year, Different Drought

Our continued dry weather and scant snow pack make it increasingly likely that 2015 will be another drought year in my part of California.  While conservation and prudent management mean that our own irrigation district (the Nevada Irrigation District, or NID) will probably make full deliveries this year, farmers and ranchers in other parts of the state aren't so fortunate.  And even with prospects for a "normal" irrigation season, we're currently dealing with the consequences of a dry January and February on our un-irrigated annual grasslands.
The contrast between grazed and un-grazed annual grasslands is
remarkable at SFREC.  I put these cow-calf pairs into this new pasture
just before taking this photograph.

The Sierra Foothill Research and Extension Center (SFREC), where I am the beef herdsman, has been monitoring annual forage production for over 30 years.  This year's March 1 measurement indicated that our forage growth is about 70 percent of normal for this time of year.  This beats last year's March 1 measurement (which was 58 percent of normal), but it doesn't tell the whole story (about either year).

Last year, we had no precipitation between early December 2013 and late January 2014 - in fact, we set a record for consecutive days without precipitation.  The autumn of 2014 was much better in terms of rain - we measured more rain in Auburn in December than we've measured since we moved there in 2001.  We had great germination in our annual grasslands, and by January 1, 2015, the green hills and oak woodlands that we graze (with sheep in Auburn, and with cattle at SFREC) were promising a better year for grass growth.
A ewe with new twins, grazing pasture that was last grazed in
November.  In a normal year, this grass would be much taller!

But then it quit raining.  We measured 0.01 inches of rain in Auburn in January.  SFREC fared a bit better - we got twice that much rain in Browns Valley!  And since we received around 3 inches of rain in early February, it's turned dry again.  As I write this, I'm seeing high clouds and a slight chance of rain in our forecast for tomorrow.

Getting back to the 70 percent of normal growth (about 475 pounds of grass per acre), this number represents our ungrazed standing crop of grass.  The pastures that we've grazed since January 1 seem to have stopped growing.  We generally expect to be able re-graze our annual grasslands every 30-35 days during the growing season (March to May), but we have yet to see the kind of recovery that makes me comfortable with regrazing.  Last year, because it rained in February, March and April, we had normal regrowth during this months.

Combined with the warmer-than-normal temperatures, much of our vegetation seems 20-30 days ahead of where it should be for early March.  The oaks have leafed out, the redbud and lilacs are blooming, and some of the annual grasses are headed out (making seeds).  By definition, annual plants must complete their life cycles (germination, growth, reproduction and death) within a year or growing season.  If it stays dry, I think our annual grasses will finish growing early.  In some ways, at least from a grazing perspective, 2015 may be tougher than 2014.
Native perennial grasses (like this purple needlegrass at
SFREC) can still be found in our foothill rangelands.

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