Why do soils become acidic?
The major causes of acidity are:
Acidic parent materials: Soils that developed from certain material such as granite are
likely to be more acidic than those developed from limestone.
Wet climate: In heavy rainfall areas, such as in Massachusetts, as water passes through
the soil, the basic soil cations including Ca, Mg, and K are gradually leached and replaced
with acid cations like Al and H+
.
Organic matter decay: Decaying of organic matter releases CO2 which reacts with water
to form acids.
Crop management: Harvesting high-yielding forages, such as corn silage or alfalfa which
both contain significant amounts of basic elements i.e. Ca, Mg, and K, has a significant
effect on soil acidity. Much more complex cations are removed by grains as compared to
leaf and stem. Application of ammoniacal nitrogen fertilizer also may influence soil acidity.