Stabilizing effect of biochar on soil extracellular enzymes after a denaturing stress

Elzobair, K.A. and Stromberger, M.E. and Ippolito, J.A. (2015) Stabilizing effect of biochar on soil extracellular enzymes after a denaturing stress. Chemosphere. 1 April 2015. Elsevier Ltd. ISSN 0045-6535 Available: http://dx.doi.org/10.1016/j.chemosphere.2015.03.01...

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Abstract

Stabilization of extracellular enzymes may maintain enzymatic activity for ecosystem services such as carbon sequestration, nutrient cycling, and bioremediation, while protecting enzymes from proteolysis and denaturation. A laboratory incubation study was conducted to determine whether a fast pyrolysis biochar (CQuest) derived from oak and hickory hardwood would stabilize extracellular enzymes in soil and prohibit the loss of potential enzyme activity following a denaturing stress, in this case microwaving. Soil was incubated in the presence of biochar (0, 1, 2, 5, or 10% by weight) for 36 days and subsequently exposed to microwave energies of 0, 400, 800, 1600, or 3200 Joules per gram of soil. Soil enzymes (ß-glucosidase, ß-D-cellobiosidase, N-acetyl-ß-glucosaminidase, phosphatase, leucine aminopeptidase, and ß-xylosidase) were analyzed by fluorescence-based assays. Biochar amendment significantly reduced the potential activity of leucine aminopeptidase and ß-xylosidase after the incubation period and prior to stress exposure. Microwaving provided stress through heat and loss of soil water, although at the lowest stress level (400 Joules per gram of soil) soil water loss was significantly reduced in soil amended with 10% biochar. Enzyme stabilization was demonstrated for ß-xylosidase, whereby intermediate biochar application rates (1 and 5 %) prevented a complete loss of this enzyme’s potential activity after soil was exposed to 400 (1% biochar treatment) or 1600 (5% biochar treatment) Joules of microwave energy per gram of soil. Potential activities of ß-glucosidase, ß-D-cellobiosidase, N-acetyl-ß-glucosaminidase, and phosphatase enzymes were not affected by biochar, and activities of these enzymes decreased significantly with increasing levels of microwave energy. We concluded that biochar has the potential to prevent evaporative losses of soil water to some degree and stabilize certain extracellular enzymes such as ß-xylosidase so that activity is maintained after a denaturing stress. This effect was dependent, however on biochar application rate and the enzyme itself. Furthermore, while biochar may reduce the potential activity of certain extracellular enzymes in soil, this phenomenon was not universal as the majority of enzymes assayed in this study were unaffected by exposure to biochar.

Item Type:	Article
NWISRL Publication Number:	1555
Subjects:	Soil > Chemistry Soil
Depositing User:	Dan Stieneke
Date Deposited:	23 Jul 2015 17:31
Last Modified:	23 Jul 2015 17:31
Item ID:	1597
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1597