Delmhorst Instrument KS-D1 - Manual (Page 7)

6
METER READING
GUIDELINES
Soil Type No Irrigation Irrigation Danger Zone
Required to be Applied Insufficient
Soil Moisture
Fine 80-100 60-80 Below 60
Medium 88-100 70-88 Below 70
Coarse 90-100 80-90 Below 80
The above guidelines are determined by the fact that different
soils have a different capacity to hold and release moisture
to the plants.
Fine textured soils (clay type) store a larger amount of water,
but they also hold a larger amount of residual water than do
coarse textured soils (sandy type). Clay soils hold more
available moisture than sandy soils. Loam and sandy
loam-type soils fall in between.
For these reasons, irrigation in sandy loam is normally
applied at higher meter readings than in clay loam soils,
since available moisture can be used up more rapidly by
the plants and dry climatic conditions in sandy loam.
There is an optimum range of moisture for optimum plant
growth. Over- irrigation, which tends to prevent adequate
root aeration and possibly lead to root rot, can be prevented
with proper irrigation scheduling. This requires recording
and observing soil moisture meter readings, recording of
rainfall, knowledge of the soil and of the crops involved.
A grower with a good understanding of soil moisture meter
readings and of all the other factors playing a role in plant
growth will, in a short time, be able to establish his own
guidelines for optimum irrigation scheduling in relation
to his soil(s), crop and climate.
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