EFFECTS OF HEATING ON THE MICROBIAL-POPULATIONS OF A GRASSLAND SOIL

Effects of burning on soil bacteria were studied under laboratory cond itions on grassland soil samples. Low intensity fire conditions were s imulated in a muffle furnace (temperature. of 450 degrees C for 3 min) . The number of aerobic heterotrophic bacteria and sporeformers was st udied in heated and unheated samples. Immediately after burning, the n umber of bacteria decreased; an increase resulted however after 24 hou rs and after 10 days. Thirty days after treatment the number of bacter ia decreased again in the treated samples, achieving values similar to the unburned soil. The laboratory procedure presented in the paper se ems to be a useful approach to simulate field conditions where fire ex periments are difficult to manage.