5 - Estimation of microbial activities

• Published in: Methods in Applied Soil Microbiology and Biochemistry pp. 193 - 270
• Format: Book Chapter
• Language: English
• Published: Elsevier Ltd 1995
• ISBN: 0125138407; 9780125138406
• DOI: 10.1016/B978-012513840-6/50020-3

The term microbial activity comprises all biochemical reactions catalyzed by microorganisms in soil. This chapter presents and discusses methods to estimate microbial activities in soil. Studies of the microbial transformation of nutrients in soils can be performed in sieved, nonaggregated soils where the mineralized nutrients accumulate. The chapter also discusses the estimation of adenosine triphosphate (ATP) in soils. It also describes the methods commonly used to estimate ATP in soils. The acidic phosphoric acid extraction method has been explained with examples, along with an explanation of the estimation of the adenylate energy charge in soil. Adenylate energy charge as an indicator of microbiological activity in soils is subjected to environmental stress. Soil respiration is a vast subject that can be determined directly in the field. The energy of reaction products is different with respect to the energy of reactants; thus, the process is accompanied by an absorption or liberation of energy in the form of heat. The difference in energy only depends on the initial and final states of the system; it is independent of the pathway of the reaction, no matter how complex the intermediate steps. Heat production is one of the most obvious changes occurring during the microbial degradation of organic matters.