Instruction Manual
HI 99121
Soil pH
Test Kit
SPECIFICATIONSSPECIFICATIONS
SPECIFICATIONS
SPECIFICATIONSSPECIFICATIONS
ISO 9000 Certified
Company since 1992
http://www.hannainst.com
Dear Customer,
Thank you for choosing a Hanna Product. Please read the instruction manual
carefully prior to use. It will provide you with necessary information for the
correct use of the kit.
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 noticeable
damage, notify your Dealer or the nearest Hanna office immediately.
Each kit is supplied with:
• HI 991000 portable pH meter
• HI 1292D pH electrode
• HI 721319 soil drill
• HI 7051M soil preparation solution
• HI 70004 buffer solution pH 4.01 (1 pc.)
• HI 70007 buffer solution pH 7.01 (1 pc.)
• HI 721312 hard carrying case
• HI 740036 100 ml plastic beaker (1 pc.)
Note: Any damaged or defective item must be returned in its original packing
materials.
Note: Read the HI 991000 instruction manual to ensure correct use of the
meter.
SOIL SOIL
SOIL
SOIL SOIL
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. T ypes of soil according to the pH value
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.
pp
HH
p
H
pp
HH
2
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).
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.
Fig. 2. Solubility of the elements according to varying pH values
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).
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
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adding lime, the effects in clay soil can last for as long as 10 years, but only 23 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)
CaMg(CO
Ca CO
3
2
3)2
39-66 26-39 13-26
49-82 33-49 16-33
54-90 36-54 18-36
Tab.1. Quantity (q/ha) of pure compound necessary to increase 1 unit of pH
High pH levels can depend on different elements, hence, there are different
methods for its correction.
- Soils rich with limestone :
Add organic matter (this is due to the fact that non-organic ameliorants such as
sulfur and sulfuric acid might not make economic sense due to the large
quantities needed).
- Alkaline-saline soils :
Alkalinity is due to the presence of salts (in particular a high concentration of
sodium can be harmful).
Irrigation washes away salts, hence, an appropriate use of irrigation can provide
positive results (drop-irrigation being the most recommended).
If alkalinity is caused by sodium, it is recommended to add substances such as
gypsum (calcium sulfate), sulfur or other sulfuric compounds (Tab.2). Also in
this case, a cost evaluation is necessary.
Soil ameliorants (pure compounds) Quantity (Kg)
Calcium chloride: CaCl2 · 2H2O85
Sulfuric acid: H2SO
4
57
Sulfur: S 19
Iron sulfate: Fe2 (SO4)
Aluminum sulfate: Al2 (SO4)
· 7H2O 162
3
3
129
Tab.2. Quantities provide the same result as 100 Kg of gypsum
Procedure for direct ground measurement
1) Dig, discarding 5 cm of topsoil
2) Perforate the soil (with HI 721319 soil drill) to a depth of about 20 cm or
more
3) If the soil is dry, moisten it with a small amount of distilled water
4
4) Wash the electrode with tap water (not distilled)
5) Insert the electrode pushing it slightly into the soil to ensure proper contact
6) Observe the measurement
7) Wash the electrode with tap water (not distilled) and (using a finger) gently
remove any soil remaining on the electrode (avoid using a rag or cloth)
8) Repeat the procedure in different locations in the field
9) Consider the average of the measured data
For best result, it is advisable to measure the pH of a soil solution, using a
sample of soil and soil preparation solution HI 7051; it is better to use this
procedure if you have to test a stony field in which you risk damaging the
electrode.
Procedure for the measurement of soil solution (1:2,5)
A) Sampling
1) Extracting Soil Sample
Take 1 sample per 1000 m2 (0.25 acre) of homogeneous area
Even for small areas, 2 samples are recommended (the more the samples,
the better the end-results, because the result is more representative)
2) Avoid extracting samples from soil presenting obvious anomalies and consider
them separately
3) Sample quantity:
Take the same quantity of soil for each sample. For example, use bags with
similar dimensions (1 bag per sample)
4) Depth of extraction:
General: dig and discard 5 cm (2") of topsoil
Herbaceous crops: from 20 to 40 cm of depth (8" to 16")
Orchards: from 20 to 60 cm of depth (8" to 24'’)
5) Spread the soil samples on the pages of a newspaper and let the soil dry in
a shady place or put it in an oven at 40° C
6) Crumble the dried soil and mix all the samples together to obtain a
homogeneous mixture, discarding stones and vegetable residues
7) From this mixture, take the soil sample for analysis
B) Soil solution preparation and measurement
1) Sift the soil at 2 mm
2) Weigh 10 gr of soil and put it in 25 ml of soil preparation solution HI 7051
(utilize the apposite beaker) or 20 gr of soil per 50 ml of soil preparation
solution HI 7051
3) Mix for 30 seconds
4) Wait 5 minutes
5) Mix again and measure the pH of the solution
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ORGANIC SUBSTRATE (PEAT AND MOULD)ORGANIC SUBSTRATE (PEAT AND MOULD)
ORGANIC SUBSTRATE (PEAT AND MOULD)
ORGANIC SUBSTRATE (PEAT AND MOULD)ORGANIC SUBSTRATE (PEAT AND MOULD)
pH measurement of organic substrates is important in greenhouses and nursery
growing pots. pH should be checked at the outset to make sure that the pH of
the substrate bought is that desired (pH can change if too much time elapses
from the date of packaging to the moment of utilization).
A) Direct Measurement in pot
If the substrate is not wet, add a little distilled water. Insert the electrode into
the soil and measure.
B) Measurement of the Organic Substrate Solution (1: 2 ratio).
Let the substrate dry;
Discard the coarse vegetable residues and pebbles;
In a beaker, prepare a solution composed of 1 part mould and 2 parts HI 7051
solution (for example: fill the beaker with the substrate up to 50 ml, press it
gently, empty the content in an other container and add 100 ml of HI 7051
solution);
Mix for 30 seconds and then wait for 5 minutes;
Mix again and measure the pH of the solution.
IRRIGATION WATERIRRIGATION WATER
IRRIGATION WATER
IRRIGATION WATERIRRIGATION WATER
The quality of irrigation water is a very important factor to consider. If the pH
value is very far from neutral (pH=7), probably, other anomalies are present.
Ranges for evaluation of water quality:
- good from 6 to 8,5
it can be utilized without problems
- sufficient from 5 to 6 and from 8,5 to 9
sensible crops could have problems
- scarce from 4 to 5 and from 9 to 10
utilize it carefully, avoid wetting the vegetation
- very scarce with pH < 4 and pH > 10
There are other anomalies that have to be identified via chemical analysis.
NUTRIENT SOLUTIONNUTRIENT SOLUTION
NUTRIENT SOLUTION
NUTRIENT SOLUTIONNUTRIENT SOLUTION
A rational fertilization is needed for optimum growth of plants in greenhouses;
the pH of a nutrient solution (water + fertilizer) has to meet the plants need.
If you have a fertirrigation system with automatic pH control, ensure that it is
functioning properly.
Check the pH of the solution distributed to the plants as well as any recycled
solutions.
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ORCHARD PLANTS
Preferred pH Range Preferred pH Range
Apple 5-6.5 Orange 5-7
Apricot 6-7 Peach 6-7.5
Cherry 6-7.5 Pear 6-7.5
Grapefruit 6-7.5 Plum 6-7.5
Grapevine 6-7 Pomegranate 5.5-6.5
Lemon 6-7 Walnut 6-8
Nectarine 6-7.5
VEGETABLES AND HERBACEOUS CULTIVATIONS
Preferred pH Range Preferred pH Range
Artichoke 6.5-7.5 Pepper 6-7
Asparagus 6-8 Early Potato 4.5-6
Barley 6-7 Late Potato 4.5-6
Bean 6-7.5 Sweet Potato 5.5-6
Brussels Sprout 6-7.5 Pumpkin 5.5-7.5
Early carrot 5.5-7 Rice 5-6.5
Late carrot 5.5-7 Soybean 5.5-6.5
Cucumber 5.5-7.5 Spinach 6-7.5
Egg Plant 5.5-7 Strawberry 5-7.5
Lettuce 6-7 String 6-7.5
Maize 6-7.5 Sugar beet 6-7
Melon 5.5-6.5 Sunflower 6-7.5
Oat 6-7 Tomato 5.5-6.5
Onion 6-7 Watermelon 5.5-6.5
Pea 6-7.5 Wheat 6-7
LAWN
Preferred pH Range
Lawn 6-7.5
GARDEN PLANTS AND FLOWERS
Preferred pH Range Preferred pH Range
Acacia 6-8 Ligustrum 5-7.5
Acanthus 6-7 Magnolia 5-6
Amaranth 6-6.5 Narcissus 6-8,5
Bougainvillea 5.5-7.5 Oleander 6-7.5
Dahlia 6-7.5 Oleander 6-7.5
Erica 4.5-6 Paulownia 6-8
Euphorbia 6-7 Portulaca 5.5-7.5
Fuchsia 5.5-7.5 Primula 6-7.5
Gentian 5-7.5 Rhododendron 4.5-6
Gladiolus 6-7 Roses 5.5-7
Hellebore 6-7.5 Sedum 6-7.5
Hyacinth 6.5-7.5 Sunflower 5-7
Iris 5-6.5 Tulip 6-7
Juniper 5-6.5 Viola 5.5-6.5
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HOUSEPLANTS
Preferred pH Range Preferred pH Range
Abutilon 5.5-6.5 Gardenia 5-6
African violet 6-7 Geranium 6-8
Anthurium 5-6 Hibiscus 6-8
Araucaria 5-6 Jasmine 5.5-7
Azalea 4.5-6 Kalanchoe 6-7.5
Begonia 5.5-7.5 Mimosa 5-7
Camellia 4.5-5.5 Orchid 4.5-5.5
Croton 5-6 Palms 6-7.5
Cyclamen 6-7 Peperomia 5-6
Dieffenbachia 5-6 Philodendron 5-6
Dracaena 5-6 Yucca 6-7.5
Freesia 6-7.5
MAN99121 10/99 PRINTED IN PORTUGAL
ISO 9000 Certified
Company since 1992
http://www.hannainst.com
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