Topic 6) Soil Acidity Flashcards
Sources of Hydrogen Ions
Carbonic Acids.
Accumulation of Organic Matter.
Oxidation of Nitrogen (Nitrifaction).
Oxidation of Sulfur .
Acids in Precipitation.
Plant Uptake in soil
Carbonic Acids
Most Common contributor to soil acidity.
Weak acid.
CO2 formed from root respiration and soil microoganisms.
Accumulation of Organic Matter
Forms soluble complexes with Cation Ca2+ and Mg2+.
Oxidation of Nitrogen
Oxidations reactions produce H+ ions.
Reduction consumes H+ ions.
Acids in Precipitation
Rain, Snow, and fog can contain acids that can contribute H+ ins
Plant up take of Cations
Plant roots exude H+ ions to balance cation uptake
How do plants maintain pH
They realse bicarbonate to maintan charge balance.
Aluminum role in soil pH
H+ ions attack sturture of mineral releasing AL3+ ions.
Then these ions become adsorbed on the CEC sites wihc mines theres more H+ in the soil
Pools of Soil Aciditiy
Activie Acidity
Exchangeable Acidity
Resdual Acidity
Active Acidity
Defined by the H+ ions active in the soil solution.
very small compared to other pools
Exchangelable Acidity
Exchangeable hydrogen and aluminiun ions.
can be released into the soil solutition by cation exchange.
Residual acidity
nonexchangebale hydrogen adn aluminun ions.
Buffering in soils
The ability to resistence the change of the pH in the soil.
How do we measure pH
pH strips
pH selective meters
Nitrogen fertilization
When nitrogen is added to the soil oxidations occurs which results in strong organic acids. So excess fertizer is harmful.
