Fire Effects on Soil Organic Matter

Soil organic matter (SOM), or humus, increases soil water-holding capacity and aggregation and typically contains 90% or more of soil nitrogen. Prescribed fire in pine forests of the southern coastal plain of the United States decreases organic matter (carbon, or C) and nitrogen (N) in the forest floor, while having either no effect or a weak positive effect on organic matter and N in the mineral soil (Table:Effects of Prescribed Burning on Soil Carbon and Nitrogen in Pine Forests of the Southern Coastal Plain.). (Little information exists on fire’s effect on C and N amounts on other ecosystems of the South.) Prescribed fire in the South has been reported to both increase and decrease the conversion of organically bound N to plant-available forms (ammonium and nitrate). Charcoal in burned soils is a relatively stable form of SOM, and may affect plant nutrient uptake and the competitive balance between plant species.

For more information on the above topics, click the links below:

• Fire Effects on Amounts of Soil Organic Matter (Carbon) and Nitrogen

• Fire Effects on the Biological and Chemical Properties of Soil Organic Matter

• Charcoal and Its Effect on Soil Properties