Soil acidification
Soil acidification is the decline of soil pH as acids accumulate or basic ions are removed. It occurs through natural processes and human activities.
Soil pH: Soil pH measures the acidity or alkalinity of soil, primarily through hydrogen-ion activity in soil solution. Its decline is the defining measure of soil acidification.
Acid deposition: Acid deposition is the transfer of acidic compounds from the atmosphere to Earth's surface in rain, snow, particles, or gases. Atmospheric inputs can acidify soils, especially where buffering is weak.
Liming (soil): Liming is the application of alkaline materials, commonly ground limestone, to raise soil pH. It neutralizes acidity and replenishes calcium in many managed soils.
Nutrient availability: Nutrient availability is the extent to which essential elements occur in forms organisms can absorb. Changing pH can restrict some nutrients while making others excessively soluble.
Soil salinization: Soil salinization is the accumulation of soluble salts in soil to levels that impair plants or soil function. Salinity is driven by salt accumulation, not by declining pH.
Cation-exchange capacity: Cation-exchange capacity is the amount of positively charged ions that soil particles can retain and exchange. Exchange sites buffer acidity by holding nutrient cations and aluminum.
Nitrogen fertilizer: Nitrogen fertilizer supplies plants with nitrogen in mineral or organic forms to support growth. Ammonium-based fertilizers can generate acidity during nitrification and subsequent ion uptake.
Agricultural soil management: Agricultural soil management is the set of practices used to maintain soil fertility, structure, water, and biological function. Managing fertilizer, crops, and amendments can prevent or correct acidification.
Soil biodiversity: Soil biodiversity is the variety of organisms living in soil and the ecological roles they perform. Acidity shifts microbial and animal communities, altering decomposition and nutrient cycling.
Alkaline soil: Alkaline soil has a pH above neutral, commonly because of carbonate or other basic compounds. It lies at the opposite end of the pH scale from acidified soil.