Hanna Instruments HI 99121 - Manual (Page 5)

9 8
ORGANIC SUBSTRATE
pH measurements 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 dry, add a little distilled water. Insert the
electrode into the soil and take measurement.
B) Measurement of the organic substrate solution (1:2)
Let the substrate dry and discard the coarse vegetable residues
and pebbles.
Prepare a solution composed of 1 part of mould and 2 parts
of HI 7051 solution (for example: fill the beaker with the
substrate up to 50 ml, press it gently, empty the content in
another 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.
NUTRIENT SOLUTION
A rational fertilization is needed for optimum plants growth in
greenhouses. The pH value of the nutrient solution (water +
fertilizer) has to meet the plants need.
If a fertirrigation system with automatic pH control is used,
ensure that it is functioning properly.
Check the pH of the irrigation solution as well as any recycled
solution.
IRRIGATION WATER
The quality of irrigation water is a very important factor. If the
pH value is very far from pH 7, it is possible that other
anomalies are present.
Ranges for evaluation of water quality:
- 6 to 8.5 pH: good, it can be utilized without problems.
- 5 to 6 pH or 8.5 to 9 pH: sufficient, sensible crops could
have problems.
- 4 to 5 pH or 9 to 10 pH: scarce, use it carefully, avoid
wetting the vegetation.
- pH<4 or pH>10: very scarce, there are other anomalies that
have to be identified via chemical analysis.
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 Paulownia 6-8
Erica 4.5-6 Portulaca 5.5-7.5
Euphorbia 6-7 Primula 6-7.5
Fuchsia 5.5-7.5 Rhododendron 4.5-6
Gentian 5-7.5 Roses 5.5-7
Gladiolus 6-7 Sedum 6-7.5
Hellebore 6-7.5 Sunflower 5-7
Hyacinth 6.5-7.5 Tulip 6-7
Iris 5-6.5 Viola 5.5-6.5
Juniper 5-6.5