Changes in Soil Properties During Heating

Critical Thresholds

 

Below 100° C (212° Fahrenheit) -  Fatal temperatures for most living organisms occur below 100° C.

• 176° - 204° C (348° - 399° Fahrenheit) – Intense water repellency (hydrophobia) is formed in soil when temperatures rise above 176° C (348° Fahrenheit).

• 220° C (428° Fahrenheit) – Complete soil dehydration occurs when temperatures reach this threhold.

• 220° - 460° C (428° - 860° Fahrenheit) – Temperatures in this range combusts organic material. This can be beneficial by providing relatively larger amounts of plant nutrients. But it has a serious disadvantage of destroying soil structure. These temperatures typically cause long term damage to soils with slow organic replacements rates (i.e., more arid soils).

• Above 460° C (860° Fahrenheit) – Temperatures at this threshold and above produce irreversible soil changes by making them less porous, less plastic, less elastic, and highly erodible.

 

Source: DeBano, L.F., Neary, D.G., & Ffolliot, P.F. (1998). Fire effects on ecosystems. New York: Wiley, p. 79.