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Date Permissions Signed

7-23-2022

Date of Award

Summer 2022

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Studies

Degree Name

Master of Arts (MA)

Department

Environmental Studies

First Advisor

Bach, Andrew J.

Second Advisor

Bunn, Rebecca

Third Advisor

LaHue, Deirdre Griffin

Abstract

I sampled Skagit silt loam soils from a field trial at the WSU NWREC where biochar and compost were added to potato crops in late spring pre-planting. Soil mesofauna were sampled at mid and late-summer, while soil microbes were sampled at late summer exclusively. Soil treatments included mixed biochar and compost, compost-only, and an unamended control. Mesofauna were extracted with Berlese funnels and sorted to functional groups. F:B ratios and total microbial C were determined using microbiometer test kits. To test whether biochar and compost induced changes to soil mesofauna communities, I used permutational ANOVA. Differences in F:B ratios and total microbial C were tested using a linear mixed effects model with ANOVA. Mesofauna communities differed markedly between mid and late-summer sampling (p=0.001) with a shift from Rhyzoglyphus, and Collembola dominance to a more even mix of functional groups including Formicidae, Psocodea, Symphyla, Apocrita, and Diptera with a diminished overall population. However, neither compost nor biochar treatments had a significant effect on soil mesofauna communities (p=0.291) nor did they alter F:B ratios and total microbial C (p=0.246 and 0.787 respectively). The microbial community favored bacterial dominance with an average F:B ratio of 0.60±0.21 across treatments and total microbial C was 272.50 µg C/g±115.82. The decrease in mesofauna abundance between mid and late summer likely reflects seasonal changes in mesofauna activity due to differences in soil temperature and moisture levels. The F:B ratio favoring bacterial dominance is indicative of chemical fertilizer use and heavy tillage which favors fast growing bacterial groups.

Type

Text

Keywords

Biochar, compost, microbes, mesofauna, Skagit, F:B ratio, mites

Publisher

Western Washington University

OCLC Number

1343756043

Subject – LCSH

Silt loam--Skagit River Valley (B.C. and Wash.); Soil invertebrates--Skagit River Valley (B.C. and Wash.); Biochar--Skagit River Valley (B.C. and Wash.); Compost--Skagit River Valley (B.C. and Wash.)

Geographic Coverage

Skagit River Valley (B.C. and Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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