ISOTHERMAL CALORIMETRY. A TOOL TO MONITORED SOIL QUALITY,

M. EUGENIA SESTO CABRAL; E. ELIZABETH SIGSTAD

Otro; Biocell.; 2006

Due to the intensive cultivation nowadays it is of great importance to handle easy, fast and precise monitoring tools to evaluate soil quality. In this sense, isothermal calorimetry is used in our labora- tory. In this work we present results obtained from a recently dismounted sandy loam soil planted with lemon trees in Tucuman, Argentina. Our aim is to monitor soil evolution due to frequent applications of 2,4-D herbicide. Samples were collected in June 2004 from 20 randomly chosen points down to 10 cm depth. Alter sieving (2 x 2 mm), water content (WC = 5.6%), field capacity hu- midity (FCH = 35.7%), pH=6.45 (soil-water, 1:1) and soil organic matter (MO = 5.5%) were determined. For calorimetric experiments 1g of soil at FCH amended with glucose or glucose Ð (NH4)2SO4 mixtures were used to find the best working conditions to monitor soil quality. Results indicate that the higher microbial activity was achieved with a 2.5 : 2.5 mg glucose (NH4) 2SO4 mixture with a glucose degradation of 52% in 15 h. When soil was amended with 5 or 10 mg of glucose, only 25% was degraded in 35h.