Concentrations of soil nutrients before and after fire.

Large amounts of nutrients from the L-H horizons and 0–2 cm of mineral soil were either redistributed at mineral soil depths or removed by leaching within a 15-month period after severe fire in jack pine barren lands in northern Ontario. Losses and redistribution by leaching were attributed to the large decrease in amount of organic matter (79 to 91%) and a decrease in exchange capacity of the L-H horizons as a result of burning. Increased solubility of the nutrients deposited in ash contributed to their vulnerability to leaching.Leaching of sodium, potassium and calcium was greatest during the first 3-month period after fire. Differential leaching resulted from the differing adsorption properties of the cations; more potassium was leached in comparison with calcium. Decreases in levels of extractable iron, aluminum and phosphorus may have been partly the result of their fixation in unavailable form, but leaching was responsible for 48% of the decrease in extractable phosphorus from the surface horizons o...