Acidification also occurs when base cations such as calcium, magnesium, potassium and sodium are leached from the soil.
Soil acidification naturally occurs as lichens and algae begin to break down rock surfaces.
Soil acidification rates can vary, and increase with certain factors such as acid rain, agriculture, and pollution.
These gases may be present in the atmosphere due to natural sources such as lightning and volcanic eruptions, or from anthropogenic emissions.
[2] Basic cations like calcium are leached from the soil as acidic rainfall flows, which allows aluminum and proton levels to increase.
[7] The decrease in pH can solubilize Al3+ that is toxic to fish,[8] especially newly-hatched fry with immature gill systems through which they pass large volumes of water to obtain O2 for respiration.
As the snow meltwater flush passes, water temperatures rise, and lakes and streams produce more dissolved organic matter; the Al concentration in drainage water decreases and is bound to organic acids, making it less toxic to fish.
This process releases OH− into soil solution and buffers the pH decrease caused by the added H+ from both acids.
[12] Acidification from leaf litter on the O-horizon is more pronounced under coniferous trees such as pine, spruce and fir, which return fewer base cations to the soil, rather than under deciduous trees; however, soil pH differences attributed to vegetation often preexisted that vegetation, and help select for species which tolerate them.
[20] Anthropogenic sources of sulfur dioxides and nitrogen oxides play a major role in increase of acid rain production.
[clarification needed] The use of fossil fuels and motor exhaust are the largest anthropogenic contributors to sulfuric gases and nitrogen oxides, respectively.
[25] At a larger scale, soil acidification is linked to losses in agricultural productivity due to these effects.
[36] Soil acidification is a common issue in long-term crop production which can be reduced by lime, organic amendments (e.g., straw and manure) and biochar application.
[26][41] Different management strategies may also be applied to prevent further acidification: using less acidifying fertilizers, considering fertilizer amount and application timing to reduce nitrate-nitrogen leaching, good irrigation management with acid-neutralizing water, and considering the ratio of basic nutrients to nitrogen in harvested crops.
[42] By reducing anthropogenic sources of sulfur dioxides and nitrogen oxides, and with air-pollution control measures, let us[who?]
[43] This has been observed in Ontario, Canada, over several lakes and demonstrated improvements in water pH and alkalinity.