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Document Type

Dissertation - University Access Only

Award Date


Degree Name

Doctor of Philosophy (PhD)


Plant Science

First Advisor

Thomas E. Schumacher


Biochar properties depend on pyrolysis process and feedstock source. Objectives of this research were to evaluate the effects of four biochars developed from two feedstocks, switchgrass (Panicum virgatum L.) and corn stover (Zea mays) using two methods of pyrolysis (fast and slow) on: 1. water holding capacity of two soil series associated with eroded landscapes in eastern South Dakota (Maddock classified as a sandy, mixed, frigid Entic Hapludolls, and Langhei classified as a fine-loamy, mixed, superactive, frigid Typic Eutrudepts), 2. germination of four plant species (corn, soybean (Glycine max), alfalfa (Medicago sativa), wild sunflower (Helianthus annuus)), and 3. phenotypic characteristics of inoculated (Rhizobium) and non-incoculated Medicago truncatula (barrel clover) genotypes “wild” and “sickle” (an ethylene insensitive mutant). Biochar treatments at a 4% application rate increased plant available water (PAW) but had no effect on water content at the permanent wilting point. There was no effect of biochar on corn, alfalfa, or soybean germination in soil. Biochars reduced wild sunflower germination 3-19%. A single gene mutant (“sickle”) of Medicago truncatula that is insensitive to ethylene was used to evaluate biochar effects on nodule formation and root morphology compared to the “wild” genotype. Biochar treatments at a 1% application rate increased nodule formation and plant biomass across all genotypes. The lack of inhibition by biochar on nodule formation in the “wild” genotype suggests that biochar did not increase ethylene concentration within the plant root to physiologically significant levels. However biochar increased root length of lower order lateral roots (0-1 mm diameter) by 40% compared to the control in the “wild” but not in the “sickle” genotype. Biochar affected soil physical, chemical, and biological properties in this study. A relatively complex interaction of biochar with plant-soil systems that depended on biochar and soil types was observed in this study. The complexity of field environments, agronomic management, and economic variables combined with complexities associated with biochar-plant-microbial-soil interactions suggest that use of biochar in crop production systems are likely to produce a variety of results. Further research is needed on elucidating mechanisms associated with biochar-crop interactions and on evaluating economic consequences of applying biochar in field situations.

Library of Congress Subject Headings

Biomass energy
Plant biomass
Plant-soil relationships
Corn stover


Includes bibliographical references (pages 144-167)



Number of Pages



South Dakota State University


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