Delmhorst Instrument Co KS-D1 User manual

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Delmhorst Instrument Co.
Model KS-D1
Operating Instructions
TABLE OF CONTENTS
1 Introduction
3 Figure 1
4 Figure 1A
5 Operating Procedure
5 Interpretation of the Meter Readings
6 Meter Reading Guidelines
7 Figure 3
8 How To Use Irrigation Charts
8 Installation of the Blocks
9 Where To Place Blocks
10 Depth Of Installation
10 Care of Your Meter
11 Service of Your Meter
12 Warranty
INTRODUCTION
The Delmhorst soil moisture measuring system consists of two parts: the gypsum
soil blocks (sensors) and the measuring instrument, Model KS-D1 moisture
tester. The blocks are made of gypsum cast around two concentric electrodes.
The gypsum acts as a buffer against the effect that the salts might have on the
electrical conductivity and the concentric electrodes confine the flow of current to
the interior of the block, eliminating the effects of soil conductivity.
When a block is buried in the soil it absorbs moisture from the soil or releases
moisture into the soil, until its moisture content approaches equilibrium with the
moisture content of the soil. When the block is connected to the meter, current
flows between the electrodes and the electrical resistance of the gypsum is
measured. Such readings are an indication of the moisture available to the
plants.
For irrigation purposes, the water of importance is that amount which can be
extracted from the soil by the roots of the plants, and not the percent moisture
content (which is related to the weight of the soil). We refer to this reservoir of
moisture as “available moisture.”
Each soil has a different capacity to hold water, depending on its structure and
texture. The maximum amount of water available to the plants (called Field
Capacity) is the amount held by the soil against drainage by gravity. When

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virtually all available water has been used (that is when no further moisture can
be extracted by the plant) soil moisture has reached the level known as the
"Permanent Wilting Point.” With soil moisture at this level, plants permanently
wilt and die.
Finely textured soils such as fine sandy loams and clay loams hold a greater
amount of water at field capacity then coarsely textured soils such as coarse
sandy loams.

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OPERATING PROCEDURE FOR KS-D1
1. To check the meter calibration: Press the “CAL CHK” button. The meter
should read 80.0 ±1.0. Note: Instrument serial numbers from 0100-0584
require pressing both “READ” and “CAL CHK” buttons simultaneously.
2. To “read” the blocks:
Push the tinned ends of the lead wires of the block into two springloaded
binding posts on the meter.
Press the “READ” button, recording the “reading” on the “Soil Moisture
Observation Chart.”
NOTE: Only readings between 5.0 and 100.0 are valid. Readings outside this
range should be disregarded.
INTERPRETATION OF METER READINGS
Meter readings are interpreted in terms of “Soil Moisture Tension,” or “Blocks
Resistance” by referring to figure 1 and 1A; in terms of “available soil moisture”
by referring to figure 2.
The data in the chart below provides guidelines of “Available Moisture” and
“Irrigation Requirements” for three groups of soil in terms of their texture make-
up.
Since soils are not strictly divided into three groups only, but changes from “fine”
to “coarse” soil are gradual, the information below should be used as a guideline.
Consideration should be given to other factors such as:
A. Type of crop;
B. Stage of crop growth and root system;
C. Climactic conditions;
D. Structure of sub-soil.

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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 ones (clay soils) store a larger amount of water, but they also hold
a larger amount of residual water than do coarse textured (sandy soils). In the
overall picture, 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 tend to prevent adequate root aeration and possibly lead to root rot, can be
prevented with proper irrigation scheduling. This entails 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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HOW TO USE IRRIGATION CHARTS
Irrigation charts are provided with each instrument. Additional charts are
available on order. Regular use of the charts helps in planning irrigation.
All readings should be recorded using a line of different identity to indicate the
readings of each particular block.
As readings are made and recorded, a curve of soil moisture changes will result.
By extending the slope of the lines, it will be possible to see well in advance
when the soil moisture will reach the level at which irrigation is required. In
addition, the chart will also indicate how much water is needed to restore the
moisture to field capacity.
To give an example, assume that irrigation should be applied when a block
planted at 18” and yielding a reading of 63, indicates roughly 1.5 in terms of bars
tension. Soon after irrigation, this block may read 96; a few days later (without
irrigation or rainfall) it may read 88; the next day 80. If these three readings are
plotted on the irrigation chart, and a line extended through them, it is possible to
project the time at which the 1.5 bars tension level (or irrigation point) will be
reached; in this case it would be less than three days.
INSTALLATION OF THE BLOCKS
1. Soak the blocks in water for 2 to 3 minutes.
2. Dig a hole in the ground with “1” soil auger or better, a 7/8” soil probe.
3. Make a soil and water slurry of creamy consistency and place 1 or 2
tablespoons of the slurry in the hole.
4. Push the block to the bottom of the hole, forcing the slurry to envelop the
block. The block can be pushed by using a tube (plastic or aluminum will
suffice) or a slotted rod.
5. Back fill the hole and tamp in small increments.

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6. Install only one block in each hole and fasten the leads to a stake so that they
can be kept clean and are easily located for reading. Identify the lead wire
according to the depth of the blocks. This can be accomplished by a colored tag
or by making a knot on the shallow block, 2 knots on the deep one (3 knots on
the next, if three blocks are used in the same station).
NOTE: It is recommended that the blocks be soaked in water for 1 hour and
allowed to dry as soon as received. This additional wetting-drying cycle will
improve their uniformity. Before “planting the blocks, they should be soaked
again for 2 to 3 minutes to improve contact with the soil.
WHERE TO PLACE BLOCKS
It is not possible to give precise instructions, which apply to all cases. The
location and depth of the blocks depends on the nature of the crops, its potential
root zone, the type of soil with regard to texture and subsurface formation, and
the profile of the field. However, there are some guidelines to be followed: (A
“string” of blocks 2, 3, or 4, depending on the depth to be reached, is called
“station”).
Locate the stations in the representative areas of the field. Don’t place the
blocks in low or high spots or near changes in slope of the irrigation run unless
you wish to measure variability in water penetration caused by such differences.
Select a station location where the plant population is representative of the field.
Keep the soil around the stations from becoming compacted when taking
readings especially where blocks are planted near the surface. Don’t walk in
furrows in which soil moisture readings are being measured. Walk in the next
furrow. Mark each “walk” furrow when installing the blocks.
When using sprinkler systems, make sure the blocks are set so they will not be
damaged when the sprinkler is moved. Inaccurate readings can also result if the
blocks are placed too close to the sprinkler head.
The blocks should not be shielded by any low hanging branches nor in an area
that may be flooded by run-off. In the case of row crops, the blocks should be
located directly in the row. As for orchards, the blocks are located at the drip line
of a tree.
It is also suggested that a second “string” of a few blocks be placed in the ground
not far from the first – 10” to 20” apart. This will serve as a control on the blocks
and on other factors. If the readings of tw2o adjacent blocks at the same depth
show a significant discrepancy, the cause should be determined. It may be poor
distribution of water from the sprinkler system, or difference in sprinkler
distribution caused by wind, differences in root concentration surrounding the
block installations, or difference in the soil.

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DEPTH OF INSTALLATION
The active root zone of the crop determines the depth at which to place the
blocks. Type of crop, soil depth, and state of growth should also be considered.
When seeds are first planted, irrigation is necessary to assure quick and uniform
seed germination. Visual inspection of the soil near the seeds will indicate
whether irrigation is needed at that time. A minimum of two blocks per station is
recommended; one shallow, one deep. The table below gives recommended
depths for setting the blocks according to soil depth or active root zone.
Recommended depths for placing electrical resistance blocks according to soil
depth or active root zones.
Soil depth or Shallow blocks Deep blocks
active root zone (Inches) (Inches)
(Inches)
18 8 12
24 12 18
36 12 24
48 18 36
CARE OF YOUR METER
To keep you’re meter in good working order:
•Store your meter in a clean, dry place. The protective carrying case is an
ideal storage place when the meter is not in use.
•Change the 9-Volt battery as needed. Continued use with a low battery may
cause the meter to go out of calibration.
•Clean the meter with any biodegradable cleaner. Use the cleaner sparingly
and on external parts only.
•Remove the battery if the meter will not to be used for one month or longer

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SERVICE FOR YOUR METER
•Pack your meter securely. Enclose a purchase order or letter with a brief
description of the problem.
•There is no need to call us for a return authorization number if you are within
the U.S. Customers outside the U.S. must contact us for more specific
instructions prior to returning a meter.
•Include your name, address, daytime phone and fax numbers or e-mail
address. If you believe the meter is under warranty, please provide the
original sales slip or invoice.
•Ship via UPS, Express Mail, Priority Mail or any overnight courier who
provides prompt service. Do not use standard parcel post.
•Insure your instrument for its full value and ship prepaid. We are not
responsible for damage in transit.
•We do not accept COD shipments or cover any incoming freight or duty
charges on returned merchandise
•Turnaround time on repairs is approximately two weeks.
•We will call you with an estimate if you specifically request one, or if we
determine that the meter may be too costly to repair.
•Non-warranty repairs will be returned via UPS/COD unless you have already
established other payment terms. There is no COD service outside the U.S.
To pay by credit card, include the card number and expiration date with your
repair. We accept Visa/MasterCard, American Express, and Discover.
•Warranty repairs will be returned at no charge if shipped within the U.S. via
UPS Ground Service. Freight charges for expedited services (i.e., Federal
Express, UPS/2 Day, UPS/1 Day, etc.) are the customer’s responsibility and
will be charged as per the above terms.

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WARRANTY
Delmhorst Instrument Co., referred to hereafter as Delmhorst, guarantees its KS-
D1 meter for one year from date of purchase and any optional electrodes against
defects in material or workmanship for 90 days. If, within the warranty period of
the KS-D1, you find any defect in material or workmanship return the meter
following the instructions in the “Service for Your Meter” section. This limited
warranty does not cover abuse, alteration, misuse, damage during shipment,
improper service, unauthorized or unreasonable use of the meter or electrodes.
This warranty does not cover batteries, pin assemblies, or pins. If the meter or
any optional electrodes have been tampered with, the warranty shall be void. At
our option we may replace or repair the meter.
Delmhorst shall not be liable for incidental or consequential damages for the
breach of any express or implied warranty with respect to this product or its
calibration. With proper care and maintenance the meter should stay in
calibration; follow the instructions in the “Care of Your Meter” section.
Under no circumstances shall Delmhorst be liable for any incidental, indirect,
special, or consequential damages of any type whatsoever, including, but not
limited to, lost profits or downtime arising out of or related in any respect to its
meters or electrodes and no other warranty, written, oral or implied applies.
Delmhorst shall in no event be liable for any breach of warranty or defect in this
product that exceeds the amount of purchase of this product.
The express warranty set forth above constitutes the entire warranty with respect
to Delmhorst meters and electrodes and no other warranty, written, oral, or
implied applies. This warranty is personal to the customer purchasing the
product and is not transferable.
Delmhorst Instrument Co.
51 Indian Lane East
Towaco NJ 07082
(800)-222-0638
www.delmhorst.com
e-mail - [email protected]
For over 50 years, Delmhorst has been the leading manufacturer of high-quality
resistance moisture meters. We offer a complete line of portable moisture meters
for woodworking/lumber, agriculture, construction and paper.
©2000, Delmhorst Instrument Co.
Rev A. 03/03