When our microbes balance the nutrients in the
soil, pH is balanced along with all the other
minerals. It doesn't matter if the pH was high
or low, when all the minerals in the soil come
into balance, pH comes into balance as well.
3. Why
it is important to maintain neutral soil pH
Problems caused by High
soil pH
High soil pH is a problem
experienced in many arid regions where there
isn't enough rainfall to leach calcium and other
base materials from the soil. High pH irrigation water
can add to the problem.
The main problem with high
pH soils is that the alkalinity can severely
limit plant growth. As soil pH increases over
7.5, the ability of certain nutrients to be
dissolved and utilized by the plant decreases.
In high pH soils, iron,
boron, zinc, manganese, copper and phosphorus
become largely unavailable to the plant. High
calcium levels that are common in high pH soil
makes it difficult for the plant to take in
magnesium and potassium, even when there is no
deficiency of these in the soil.
To make the situation even
worse, alkaline soils can also hinder
micronutrient uptake by the plant. The resulting
deficiency can cause stunted plant growth.
Typically, even sulfur
applications can take a long time to lower soil
pH.
Problems caused by Low
soil pH
Similar to high pH soils,
the greatest problem caused by low pH soils is
nutrient uptake. In very acidic soils,
phosphorus, potassium, nitrogen, sulfur,
manganese and calcium become tied up in the soil
and are not as available to the plant, in spite
of the application
of fertilizers. This
usually results in less plant growth.
Microbial activity is
decreased and legumes will not nodulate as well.
Although the soil is inoculated with rhizobia
bacteria, these will not thrive in an acidic
soil, causing legumes to vanish from the soil.
Ammonium nitrate
applications can increase the problem of low
soil pH. Excess nitrogen tends to leach from the
soil, leaving behind hydrogen ions that increase
soil acidity.
Acidic soil gives the roots
less access to nutrients and water. As pH drops,
aluminum becomes more soluble. Aluminum
diminishes the growth of roots, which decreases
the nutrients available to the plant. This will
reduce plant size and size of the grain.