EFFECT OF THE CHCl3 AND MeOH EXTRACTS OF IXORRHEA TSCHUDIANA FENZL ON SOIL MICROBIAL ACTIVITY. A CALORIMETRIC ANALYSIS

SESTO CABRAL ME; SIGSTAD EE.

Jornada; JORNADAS DE LA ASOCIACION DE BIOLOGIA TUCUMAN; 2008

Ixorrhea tschudiana (Borraginaceae) is an endemic species in Tucumán, Argentina. The CHCl3 and MeOH extracts from its aerial parts were incorporated into soil to assess their effect on microbial activity. Aliquots of loam soil (110g) were placed in pots (105 cm3) contained in a plug. Water (25 ml) containing the extract was added to the pots to achieve extract concentrations of 2 x 0 (control), 2 x 100, 2 x 250 and 2 x 500 mg kg-1 and left at room temperature. After 2 months soil samples were analyzed for: organic matter (OM), pH, field capacity humidity (FCH), colony formation units (CFU g-1) and calorimetrically to obtain the thermodynamic parameters. An isothermal calorimeter of the heat conduction type was used at 25ºC. The preliminary results indicate that the microbial activity of soil amended with 100 and 250 mg kg-1 of CHCl3 and with 250 mg kg-1 of MeOH extracts of I. tschudiana is altered remaining still unclear if this modification is beneficial or detrimental for the soil.