Soil Acidification土壤酸化
Soil acidification is the process by which soil pH falls and exchangeable acidity increases. It is caused mainly by the long-term over-application of ammonium nitrogen fertilizer, acid deposition, and the accumulation of hydrogen ions from organic matter mineralisation. Acidification reduces phosphorus availability and mobilises harmful aluminium and manganese ions.
Key points
- Nitrification of ammonium nitrogen releases hydrogen ions: each unit of ammonium nitrogen applied generates a corresponding quantity of acidity in the soil, which is the principal anthropogenic cause of acidification in agricultural soils.
- After acidification, phosphorus availability falls markedly because phosphorus is readily fixed by mobilised aluminium and iron into forms the crop cannot use.
- Below about pH 5.5, mobilised aluminium becomes toxic to roots, a major reason for poor crop performance on acid soils.
- Remediation involves applying alkaline materials such as lime or dolomite — that is, soil conditioners — with the rate determined from soil testing rather than estimated.
Related terms
Soil Conditioner
A soil conditioner is a material applied to soil to improve its physical…
Nitrogen Fertilizer
A nitrogen fertilizer is one whose primary function is to supply nitroge…
Calcium Magnesium Phosphate
Calcium magnesium phosphate is a citrate-soluble phosphate fertilizer ma…
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- Category：Soil
- Definition basis：Huang Changyong & Xu Jianming (eds.), Soil Science (China Agriculture Press)
Updated：Oct 19, 2026