Difference between revisions of "PH"
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Source: [http://en.wikipedia.org/wiki/Natural_Resources_Conservation_Service The United States Department of Agriculture Natural Resources Conservation Service] | Source: [http://en.wikipedia.org/wiki/Natural_Resources_Conservation_Service The United States Department of Agriculture Natural Resources Conservation Service] | ||
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== Plant pH preferences == | == Plant pH preferences == | ||
Revision as of 08:08, 15 January 2012
- Topic in Gardening courses
Soil pH is a measure for how many H+ ions a soil contains. pH is a measure of how acidic or basic things are.
pH is defined as the negative logarithm (base 10) of the activity of hydrogen ions (H+) in solution. It ranges from 0 to 14, with 7 being neutral. A pH below 7 is acidic and above 7 is basic.[1] A pH of 6 means that there are 10 times more H+ ions in the soil compared to pH 7, while, for example, a pH of 3 means that there are 10,000(104) times more H+ ions in solution compared to pH 7.
Substances such as lemon juice and battery acid are acidic and fall in the 0-7 range, whereas seawater and bleach are basic (also called "alkaline") and fall in the 7-14 pH range. Pure water is neutral, or 7 on the pH scale.
Soil pH controls many chemical processes that take place in the soil. It specifically affects plant nutrient availability by changing the chemical form in which these nutrients are available. The optimum pH range for most plants is between 6 and 7.5, but many plants have adapted to pH values outside this range.
Classification of soil pH ranges
A peaty soil is acid. Some clay soils are neutral. Chalky soils are alkaline or basic or limey.
| Denomination | pH range |
|---|---|
| Ultra acid | <3.5 |
| Extreme acid | 3.5 - 4.4 |
| Very strong acid | 4.5 - 5.0 |
| Strong acid | 5.1 - 5.5 |
| Moderate acid | 5.6 -6.0 |
| Slight acid | 6.1 -6.5 |
| Neutral | 6.6 - 7.3 |
| Slightly alkaline | 7.4 - 7.8 |
| Moderately alkaline | 7.9 - 8.4 |
| Strongly alkaline | 8.5 -9.0 |
| Very strongly alkaline | >9.0 |
Source: The United States Department of Agriculture Natural Resources Conservation Service
Why soils become acidic
Plant pH preferences
- This list is still under construction and needs to be checked with various sources
- pH 4.5-5.0 Blueberry, Bilberry, Heather, Cranberry, Orchid, Azalea
- pH 5.0 - 5.5 Parsley, Potato, Heather, Pine, Maize, Radish, Ferns, Iris, Rhododendron
- pH 5.5 - 6.0 Bean, Brussels Sprouts, Carrot, Endive, Rhubarb, Soybean, Aster, Begonia, Daffodil, Zucchini, most bulbs
- pH 6.0 - 6.5 Broccoli, Cauliflower, Cucumber, Egg Plant, Hemp, Pea, Pumpkin, Tomato, Turnip, Clover, Gladiolus, Poppy, Rose, Viola, Wallflower, Zinnea, Strawberry
- pH 6.5 - 7.0 Asparagus, Beetroot , Cabbage, Celery, Lettuce, Melons, Onion, Parsnip, Spinach, Alfalfa, Chrysanthemum, Dahlia, Sweet Pea and Tulip.
- pH 7.1 - 8.0 Lilac, brassica
See also
References
External links
- Soil pH Wikipedia
- Understanding and Correcting Soil Acidity by Jeff Ball, The Samuel Roberts Noble Foundation
