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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).
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.
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
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.
other hand, are readily available in a pH range close to neutrality.
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
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).
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).
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,
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
Fig. 2. Solubility of the elements according to varying pH values