Product Manual

13
a number of crops provided there is increased fertilization and proper irrigation. With corn, for
example, increased fertilization alone produced no benefits, but with increased – and controlled –
irrigation, yields were more than doubled.
Controlled irrigation is just as beneficial in increasing quality and insuring early maturities as in
increasing yields. IRROMETERS are used extensively by the United States Department of Agriculture,
state experiment stations, and large commercial growers with fruits and vegetables, sugar cane,
tobacco and other crops. In one project with sweet corn, yield was improved and the crop was ready
for market two weeks earlier by increasing fertilization and maintaining readily available soil moisture
during the critical early period of growth.
We are continually collecting data on progress in these fields which is available upon request.
Saving Water/Energy
It is never recommended that a direct attempt be made
to save water by reducing soil moisture below optimum
conditions for plant growth. The proper use of
IRROMETERS allows you to eliminate the guesswork
involved in irrigation scheduling and usually results in
reducing irrigation cost.
Wetting soil might be compared to wetting a sponge.
The sponge will hold only so much water and will
absorb that water in a few seconds. Holding it under
the faucet for an hour will neither cause it to absorb
more water nor hold that water longer. Soils take longer
to absorb water but the same principle applies. Any
excess water applied is wasted by deep percolation or
run-off. By far the greatest waste is usually due to
percolation because this loss is not visible.
Probably the greatest saving in water affected by IRROMETER control results from saving
unnecessary and excessively heavy irrigations. Most growers find that they had previously been
holding certain sections “under the faucet” far longer than necessary at times, while other sections
may have been short of water. Correcting these conditions – using water where, when and in the
amount needed – often results in surprisingly large net savings of water at the end of the year.
However, it is not unusual to find that more water is required, in some sections, during some periods.
In soils where there is a very slow rate of infiltration, seepage to the level of the ceramic tip on the
“deep” instrument may take two or three days. The drop in gauge readings will be delayed accordingly.
Under these conditions, a substantial saving in water can be effected by applying half the water used
previously and waiting to see whether this brings gauge readings on the “deep” instruments down to
field capacity, instead of continuing to irrigate right up to the time that penetration is registered on the
gauge. Experience over two or three irrigation cycles will indicate the minimum amount of water
required to insure penetration to the lower root zone. Also in these soils, there is usually a material
saving in water, if irrigations start while there is still considerable moisture in the soil. Water penetrates
moist soil much more rapidly than dry soil, so less water is required to infiltrate to the lower root zone.
It is usually found that gauge readings on the “shallow” instrument rise much faster than on the “deep”
instrument, due to higher plant use of water in the feeder root zone and to surface evaporation. If
readings on the deep instrument indicate that there is adequate soil moisture at this level, water is
saved by applying only enough water to bring down the readings on the “shallow” instruments.
Under some conditions, water is saved by irrigating alternate furrows, during at least part of the
irrigation season.
In hillside plantings, IRROMETERS placed at upper and lower locations frequently indicate