BOARD02267

• Board Meeting Date: 5/27/1968
• Description: Agenda or Table of Contents, Minutes, Memos
• Board Meetings - Doc Type: Meeting

I

One point as far as irrigation agriculture
is concerned deals with something that we don't
know too much about as yet and we are working on
it. This deals with the efficiency of water
used in relation to the actual amount of produc-
tion we can obtain per unit of water that is
actually used and transpired, or consumed in
other words, b}" the plant. We have :bad a
tendency in the past to attempt to develop
maximum yields. Perhaps where we have limited
water supplies or where water is sufficiently
expensive, we should not be shooting for maxi-
mum yields but should rather be shooting for
maximum production per unit of water. There is
a possibility, we think, in growing a crop where
we do not obtain maximum production but where,
by having somewhat less than maximum, we can
get a considerably greater production per unit
of water consumed. This involves such things
as causing that plant to be under some stress
conditions during certain stages of its develOp-
ment. We don't know very much about this as
yet. We are working on it.

Along with this type of study then, we
have become well involved with such things as
transpiration from plants, evaporation from
water surfaces, transport of water through the
soil, into the soil and through the soil by
unsaturated conductivity as we call it. We
have been interested, of course, to a great
extent with various factors that cause evapora-
tion losses from the soil surface as well as
those evaporation losses from the plant tissues
or the plant leaves.

I

Under dry-land conditions we have known
for years that summer fallowing is a type of
water conservation practice. It has been
practical. It certainly has been used for a
long time and yet we know that the efficiency
of summer fallowing is extremely low. Figures
vary of course, as you might expect they
would, depending upon years, area, soil types
and all this type of thing but they range in
the order of 15 to 30 percent of the water tl:).at