Wednesday, April 9, 2014

Drought Update - April 10, 2014

Yesterday afternoon, I helped our local farm advisors, Roger Ingram and Cindy Fake, install matrix blocks in an irrigated pasture that we graze here in Auburn.  The matrix blocks allow us to track soil moisture - and to time our irrigation accordingly.  Ultimately, this should help us use our water more efficiently - we'll only irrigate when the grass needs water.
Cindy Fake installing matrix blocks in our pasture.

As they dug a hole with a soil auger (we went down 18 inches), both Roger and Cindy remarked about how dry the soil profile was - especially considering the rainfall we'd had last week.  Roger said that the soil conditions were more like mid-May than early April.  I suspect that even with the rain we've had since late January, our soils were so dry that we've just never caught up.

The condition of our annual rangeland pastures supports this hypothesis.  We try to balance supply (grass) with demand (the number of sheep we have grazing).  We express supply in terms of sheep days per acre - that is, how many sheep can graze for one day on one acre.  Typically, by early April, we expect to get 150-200 sheep days per acre (which means our 150 ewes should be able to stay 3 days on a 3-acre paddock).  Some of the pastures we've grazed in the last two weeks have only had 50-60 sheep days per acre - and we even grazed one paddock last week that had 25 sheep days per acre - the 2 acre paddock lasted 12 hours!

I realized today that looking at our rangelands at a landscape level can be deceptive.  Looking across the hillside at our grazing sheep, it looks like we have plentiful green grass.  Looking straight down, however, I begin to see bare ground and stunted plants.  I expect the pasture I moved the ewes into this morning (about 3 acres) will last about a day and a half - in other words, it's about 75 sheep days per acre.

We're fortunate to be able to move our sheep to grass.  We have the advantage of having the management and stockmanship skills - and portable fencing systems - that allow us to take advantage of pastures that other producers can't graze.  Even so, I'm still worried about the fall.  The pasture in these photos has been rested for 48 days - normally enough to grow a substantial amount of grass this time of year.  The fact that much of this grass has regrown less than 6 inches is worrisome.

The landscape view - looking across a new hillside paddock.

Looking down - my hat gives this photo some proportion.  The grass is short!

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