Hanna Instruments HI 99121 User Manual
Instruction Manual
HI 99121
Soil pH Test Kit
SPECIFICATIONS
www.hannainst.com
PRELIMINARY EXAMINATION
Dear Customer,
Thank you for choosing a HANNA instruments® product.
Please read this instruction manual carefully before using the
instrument. This manual will provide you with the necessary
information for correct use of the instrument, as well as a more
precise idea of its versatility.
If you need additional technical information, do not hesitate to email us at tech@hannainst.com.
This instrument is in compliance with the directives.
TABLE OF CONTENTS
Remove the test kit from the packing material and examine it
carefully to make sure that no damage has occurred during
shipping. If there is any damage, immediately notify your dealer.
Each kit includes:
• HI 99121 portable pH meter
• HI 1292D pH electrode
• pH 4.01 & pH 7.01 buffer solutions (20 mL each)
• HI 700663 cleaning solution for inorganic soil deposits
• HI 700664 cleaning solution for organic soil deposits
• HI 7051M soil preparation solution
• HI 721319 ground auger
• 3 x 1.5V AA alkaline batteries
• instruction manual
• rugged carrying case
Note: Save all packing material until you are sure that the
instrument functions correctly. All defective items must
be returned in the original packing with the supplied
accessories.
WARRANTY
PRELIMINARY EXAMINATION ........................................... 3
WARRANTY ......................................................................... 3
SOIL pH ............................................................................... 4
ORGANIC SUBSTRATE ...................................................... 8
IRRIGATION WATER........................................................... 8
NUTRIENT SOLUTION........................................................ 8
pH METER SPECIFICATIONS...........................................11
OPERATING THE pH METER ...........................................12
pH MEASUREMENT & CALIBRATION ..............................13
METER SETUP...................................................................14
ELECTRODE CLEANING ...................................................15
BATTERY REPLACEMENT................................................15
All Hanna Instruments meters are warranted for two years against
defects in workmanship and materials when used for their intended
purpose and maintained according to instructions. The probes are
warranted for a period of six months.
This warranty is limited to repair or replacement free of charge.
Damage due to accidents, misuse, tampering or lack of prescribed
maintenance are not covered.
If service is required, contact the dealer from whom you purchased
the instrument. If under warranty, report the model number, date of
purchase, serial number and the nature of the problem.
First obtain a Returned Goods Authorization number from the Customer Service department, then return the instrument with the
Authorization number included along with shipment costs prepaid.
If the repair is not covered by the warranty, you will be notified of
the charges. When shipping any instrument, make sure it is properly
packaged for complete protection.
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SOIL pH
pH is the measure of the hydrogen ion concentration [H+]. Soil
can be acid, neutral or alkaline, according to its pH value.
Fig. 1 shows the relationship between the scale of pH and
types of soil. Most plants prefer a pH range from 5.5 to 7.5;
but some species prefer more acid or alkaline soils.
Nevertheless, every plant requires a particular range of pH,
for optimum growth.
Fig. 1. Types of soil according to the pH value
Each plant needs elements in different quantities and this is the
reason why each plant requires a particular range of pH to
optimize its growth.
For example, iron, copper and manganese are not soluble in
an alkaline environment. This means that plants needing these
elements should theoretically be in an acidic type of soil.
Nitrogen, phosphorus, potassium and sulfur, on the other
hand, are readily available in a pH range close to neutrality.
Furthermore, abnormal pH values, increase the concentration
of toxic elements for plants. For example, in acid conditions,
there can be an excess of aluminum ions in such quantities
that the plant can not tolerate.
Negative effects on chemical and physical structure are also
present when pH values are too far from neutral conditions
(break up of aggregates, a less permeable and more compact
soil).
pH strongly influences the availability of nutrients and the presence
of microorganisms and plants in the soil.
For example, fungi prefer acidic conditions whereas most
bacteria, especially those supplying nutrients to the plants,
have a preference for moderately acidic or slightly alkaline
soils. In fact, in strongly acidic conditions, nitrogen fixing and
the mineralization of vegetable residual is reduced.
Plants absorb the nutrients dissolved in the soil water and the
nutrient solubility depends largely on the pH value. Hence, the
availability of elements is different at different pH levels (Fig.2).
Fig. 2. Solubility of the elements according to varying pH
Management of the soil in relation to the pH value
Once the pH value is known, it is advisable to choose crops
that are suitable for this range (e.g. in an acid soil, cultivate
rice, potato, strawberry).
Add fertilizers that do not increase acidity (for example urea,
calcium nitrate, ammonium nitrate and superphosphate) or
lower alkalinity (e.g. ammonium sulfate).
It is recommended that a cost evaluation is made prior to
commencement of the soil pH modification. Corrective
substances can be added to modify the soil pH, however, the
effects are generally slow and not persistent. For example, by
adding lime, the effects in clay soil can last for as long as 10
years, but only 2-3 years in a sandy soil.
For an acid soil, we can use substances such as lime, dolomitic,
limestone and marl, according to the nature of the soil (Tab.1).
Soil Ameliorants Clay soil Silty soil Sandy soil
CaO 30-50 20-30 10-20
Ca(OH)
2
CaMg(CO3)
Ca CO
2
3
Tab.1. Quantity (q/ha) of pure compound necessary to in-
crease 1 unit of pH
39-66 26-39 13-26
49-82 33-49 16-33
54-90 36-54 18-36
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