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Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Plant, Soil & Insect Sciences

Year Degree Awarded

2015

Month Degree Awarded

September

First Advisor

Dr. Baoshan Xing

Second Advisor

Dr. Masoud Hashemi

Third Advisor

Dr. Jeffrey Blanchard

Subject Categories

Agricultural Science | Other Environmental Sciences | Soil Science

Abstract

Soil quality has become a major factor used in assessing sustainable land management and the overall environmental quality, food security, and economic viability of agricultural lands. Recently, biochar has been touted as having many potential uses as a soil amendment for improving soil quality, specifically improving cation exchange capacity, pH and nutrient availability. However, soil biology also plays a significant role in biogeochemical processes that influence soil health and should be included in a more comprehensive study of soil health. This dissertation describes 4 projects within the same 3-year field study with the cumulative purpose of better understanding the effect that the application of a hardwood biochar has on soil health and quality. (1) The evaluation of a hardwood lump charcoal production by-product for use as a quality biochar amendment, tested the hypothesis that this byproduct has physical and chemical properties that fall within the range of quality biochar amendments as proposed by recent literature. (2) A three-year assessment of the changes to the soil chemical and physical properties as affected by the addition of the hardwood biochar to agricultural soils. Biochar application did not significantly affect sweet corn yield or quality. (3) A three-year assessment of the yield of sweet corn grown in the same biochar amended soils with and without added nitrogen fertilization also showed that a two percent by weight application of hardwood biochar improved yields of sweet corn, but greater application rates had a negative priming effect. Thus, testing the hypothesis that biochar would improve agronomic yields. In year three of this field study, nematode community assemblages were identified and compared in both the control and highest biochar treatments. Nematode communities were significantly different with maturity indices indicating greater temporal stability in the biochar-amended soils. The bacterial diversity of the control, two percent and four percent biochar-amended field soils were assessed using high-throughput sequencing of 16S rRNA and taxonomic assessment. While overall community diversity was not significantly affected, the abundance of specific bacterial taxa were significantly affected, indicating the potential for shifts in biogeochemical cycling in biochar-amended soils.

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