Thursday, February 24, 2011

How You Reduce Water Use Matters

Guess I have to hit this issue again because no action seems to be on anyone's planning calendar as of yet. 

The issue is the design of the Federal EQIP and AWEP programs which are supposed to be, in part, helping producers and states conserve water use.  They are doing OK - at least the way we're using them in Kansas, but they could be even better.

No one doubts the positive relationship between water application and crop production. Every Ag school in the nation produces crop production curves showing the normal yield associated with each additional inch of water made available to the crop - either by irrigation or by nature.  And all the curves look more or less the same - a steeper curve for the first 60-70% of the crop ET, then a flattening curve until it actually starts dropping when too much water is applied.  A grain crop production curve from Elsie, NE is provided above - click to enlarge.  Every crop in every climate has such a production curve.

If this is the case, it makes perfect sense that any decision to reduce water use in ag should reduce the least efficient water use from several users rather than the full water use from any user(s).  In other words, reducing 20% of water from 5 users will be the same amount of water reduction as reducing 1 water user fully (as long as they're all using the same amount) - but the former approach will yield more production at the end of the year than the latter.  This is because every inch of the reduced water in the first approach was being applied at the top of the production curve - when the crop's yield response is at its lowest.  There are actually other reasons such an approach is better economically, but not enough space to go into these now.  

Right now, EQIP and AWEP are only available to conserve water through the set aside of full water rights.  This, of course, is not as efficient a reduction of water use than if we could have more people involved in the reductions as suggested in the first approach.  I'll continue to work on NRCS to promote this relatively minor tweak in their programs.  I'd appreciate any help I can get because thus far they don't seem to be all that interested in this idea.

Again, we can conserve the same amount of water either way, but with more producers saving smaller amounts of water, our production levels are not reduced as much, and this is quite a bit better for the local economy.

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