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Addition of activated switchgrass biochar to an aridic subsoil increases microbial nitrogen cycling gene abundances

Ducey, Tom and Ippolito, J.A. and Cantrell, K.B. and Novak, J.M. and Lentz, R.D. (2013) Addition of activated switchgrass biochar to an aridic subsoil increases microbial nitrogen cycling gene abundances. Applied Soil Ecology. 65:65-72.

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Abstract

It has been demonstrated that soil amended with biochar, designed specifically for use as a soil conditioner, results in changes to the microbial populations that reside therein. These changes have been reflected in studies measuring variations in microbial activity, biomass, and community structure. Despite these studies, very few experiments have been performed examining microbial genes involved in nutrient cycling processes. Given the paucity of research in this area, we designed a six-month study in a Portneuf soil (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid) treated with three levels (1%, 2%, and 10% w/w ratio) of a biochar pyrolyzed from switchgrass (Panicum virgatum) at 350°C and steam activated at 800°C to measure the abundances of four genes involved in nitrogen (N) cycling. Gene abundances were measured using qPCR, with relative abundances of these genes calculated based on measurement of the 16S rDNA gene. At the end of the six-month study, all measured genes showed significantly greater abundances in biochar amended treatments as compared to the control, potentially increasing the amount of N cycled in soils receiving such treatments. In soil amended with 10% biochar, genes involved in nitrogen fixation (nifH), and denitrification (nirS), showed significantly increased relative abundances. Lastly, gene abundances and relative abundances correlated with soil characteristics, in particular nitrate nitrogen, % N and % carbon. In toto, these results confirm that activated switchgrass-derived biochar, designed for use as a soil conditioner, has an impact on the treated soils microbial communities. We therefore suggest that future use of biochar as a soil management practice should take into account not only changes to the soil's physiochemical properties, but its biological properties as well.

Item Type: Article
NWISRL Publication Number: 1481
Subjects: Soil > Amendments
Soil > Chemistry
Soil > Chemistry > Nitrogen
Soil
Depositing User: Michelle Wayment
Date Deposited: 30 Jan 2014 23:21
Last Modified: 03 Mar 2014 21:33
Item ID: 1517
URI: https://eprints.nwisrl.ars.usda.gov/id/eprint/1517

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