The pH of Soils
The pH scale runs from 0 to 14. The 0 end of the scale is the acid end and the 14 represents the alkaline end. A soil that tests with a pH of 7.0 is completely neutral. The correct pH of soil for the type of plants being grown can mean a bountiful harvest whereas an incorrect pH can mean unhealthy, stunted vegetables, flowers, shrubs, and even trees. Does this Spark an idea?
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Testing pH
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The term pH refers to the measurement of hydrogen-ion activity. Every farmer or gardener should know the pH of the soil being planted, and it's easy to test. Old-time methods required tasting the soil. A sour flavor indicated an acidic soil to the farmer, while a bitter taste indicated the soil was too alkaline for a healthy crop. A sweet taste meant the soil was just right. Today the farmer and gardener have an exact method for testing the soil and getting the numbers on the pH scale instead of guessing. Soil test kits are inexpensive and available at garden centers. Agricultural Extension Offices throughout America offer soil tests free or for a small fee.
Importance
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Most vegetables, flowers, and fruits grow best on soil with a slightly acid to neutral pH (6.5 to 7.0). If plenty of organic matter is present or added to the soil, plants can grow well on soil with a slightly lower or higher pH. A soil that is too acid means that the bacteria which decompose organic material cannot thrive. Nutrients to the plants are less available and they may starve, while other minerals may be too strong and toxic to the plant. Alkalinity causes the loss of soil structure and quickly dissolves humus, making the nutrients unavailable to the plant. Alkalinity also causes a concentration of salts in the soil which can stop a plant from growing.
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Adjusting Acidic Soil
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Rhododendron shrubs prefer an acidic soil. The gardener should not adjust away from a slightly acidic pH until checking the specific needs of the plant. Supplementing the soil with dolomite lime, wood ash or crushed oyster shells corrects excess acidity.
Adjusting Alkaline Soil
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Nasturtiums favor a moderate alkaline soil. Alkaline soil is adjusted towards neutral by adding large quantities of fresh organic matter such as manure, compost, leaves, peat moss, pine needles and grass clippings.
Considerations
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Some plants actually grow best in an acidic soil of pH 4 to 6. Some ornamental selections liking this soil are azaleas, rhododendrons, chrysanthemums and marigolds. A few of the plants producing an edible crop that prefer an acidic medium include cranberries, blueberries, watermelon, sweet potatoes and peanuts. Grain crops such as wheat, barley maize and sugar cane are tolerant of an alkaline soil. Common backyard plants that grow well in moderate alkaline soil are beans, beets, cabbage, peas, sweet peas, nasturtium and iris and many more.
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References
Resources
- Photo Credit tilled field image by Niki from Fotolia.com rhododendron image by reises from Fotolia.com Orange nasturtium in garden image by radarreklama from Fotolia.com
