The relationship between pH,soil health and plant growth
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The pH scale ranges from 0-14
*Alkaline soils are also called Base, Basic, or Salty
A pH below 7 is acidic
A pH of 7 is neutral
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A pH above 7 is alkaline
Soil pH refers to the acidity or alkalinity of soil
Reference: pH Scale
What is soil pH?
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Each plant has a preferredsoil pH level for optimal growth
If the preferred pH level is not met,it may cause stunted growth or death
Examples >>
Preferred pH levels for common produce:
Nutrient Table
Some nutrients
(Fe, Zn, Al, Mn)
are available for uptake by plants below pH 5.0,
but their availability can be excessive and toxic in acidic conditions.
In alkaline conditions, nutrients are less available causing nutrient deficiency symptoms
Way Too Acidic
As the pH level changes, it affects the availability of nutrients to the plant.
Click below to explore the various pH scenarios.
Too Acidic
Most nutrients are available at a pH of 5.5-7.
pH Balanced
Too Alkaline
When the pH falls below 5.5,
most major plant nutrients
(N, P, K, S, Mg, Ca)
become insoluble and unavailable for uptake by plant roots.
Clubroot disease occurs in highly acidic soils.
Extremes in pH
for Plants
Clubroot
Extremes in pH
for Diseases
Extremes in pH cause or exacerbate plant diseases.
Extremes in pH make essential nutrients unavailable to crops, weakening them and making them more susceptible to disease.
Potato Scab
How pH Affects Plant Diseases
Some plant diseases thrive in extreme pH conditions.
Potato scab occurs in highly alkaline soils.
Too Acidic/Alkaline
Balanced/Neutral
Fungi and anaerobic bacteria, generally detrimental, have a broad pH tolerance and multiply rapidly at acidic pH levels
Acidic soils cause sour spoiling of soil organic matter instead of healthy decay
Most soil bacteria prefer a pH level of around 6.3-6.8
Earthworms, beneficial for soil aeration and rapid decay of organic matter, prefers soil conditions near neutral
Other fertilizers containing Ca, K, and Na increase pH.
Some fertilizers can make soils more acidic.
Soil pH can vary within a region depending on factors such as slope, rocks, and vegetation type
Therefore, pH should be measured regularly and at various locations within the land in question
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How the Environment Affects pH
Soils tend to be more acidic in regions of high annual rainfall.
Soils tend to be alkaline in regions of low annual rainfall.
Soils with high organic matter decomposition tend to be more acidic.
Soil pH can vary throughout the season depending on factors such as rainfall and organic matter content