Soil ph. Why is soil acidic and what determines it acid. Why is soil alkaline, ?

Question

Why is soil acidic,? the certain properties of acidic soil.

alkaline soil? why is soil alkaline, is it alkaline because it needs more nutrients? less nutrients? etc please give me as much of ur knowledge as possible. thanks

Answer 1

sometimes soil is acidic because of the acidic residue from dropped leaves , say like tannic acid from oak leaves.

often soil is acidic or alkaline because of the salts that are present in the soil

soil with sodium or potassium carbonates are quite alkaline, because of the hydrolysis of the carbonate with water:

CO3)-2  & water => HCO3)-1 & OH- (basic)

& so it is with minerals that can form a weak acid with their negative ion, they form alkali soils when in contact with water, (they release OH- from the water)

soil with calcium or magnesium sulfates are quite acinic, becaue of the hydrolysisof the Ca+2 or the Mg+2 with the water:

Ca+2  & water -->  Ca(OH)2 (s)  & 2 H+ (acidic)

& so it is with minerals that can form a weak bases with their positive ion, they form acid soils when in contact with water, (they release H+ ions from the water)