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Dive into the research topics where Duff R. Harrold is active.

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Featured researches published by Duff R. Harrold.


Waste Management | 2016

Assessment of tomato and wine processing solid wastes as soil amendments for biosolarization.

Yigal Achmon; Duff R. Harrold; Joshua T. Claypool; James J. Stapleton; Jean S. VanderGheynst; Christopher W. Simmons

Pomaces from tomato paste and wine production are the most abundant fruit processing residues in California. These residues were examined as soil amendments for solarization to promote conditions conducive to soil disinfestation (biosolarization). Simulated biosolarization studies were performed in both aerobic and anaerobic soil environments and soil temperature elevation, pH, and evolution of CO2, H2 and CH4 gases were measured as metrics of soil microbial activity. Tomato pomace amendment induced conditions associated with soil pest inactivation, including elevation of soil temperature by up to 2°C for a duration of 4days under aerobic conditions and a reduction of soil pH from 6.5 to 4.68 under anaerobic conditions. White wine grape pomace amendment showed similar trends but to a lesser extent. Red wine grape pomace was generally less suitable for biosolarization due to significantly lower soil temperature elevations, reduced acidification relative to the other pomaces and induction of methanogenesis in the soil.


Pest Management Science | 2017

Weed seed inactivation in soil mesocosms via biosolarization with mature compost and tomato processing waste amendments.

Yigal Achmon; Jesús D. Fernández-Bayo; Katie Hernandez; Dlinka G. McCurry; Duff R. Harrold; Joey Su; Ruth M. Dahlquist-Willard; James J. Stapleton; Jean S. VanderGheynst; Christopher W. Simmons

BACKGROUND Biosolarization is a fumigation alternative that combines passive solar heating with amendment-driven soil microbial activity to temporarily create antagonistic soil conditions, such as elevated temperature and acidity, that can inactivate weed seeds and other pest propagules. The aim of this study was to use a mesocosm-based field trial to assess soil heating, pH, volatile fatty acid accumulation and weed seed inactivation during biosolarization. RESULTS Biosolarization for 8 days using 2% mature green waste compost and 2 or 5% tomato processing residues in the soil resulted in accumulation of volatile fatty acids in the soil, particularly acetic acid, and >95% inactivation of Brassica nigra and Solanum nigrum seeds. Inactivation kinetics data showed that near complete weed seed inactivation in soil was achieved within the first 5 days of biosolarization. This was significantly greater than the inactivation achieved in control soils that were solar heated without amendment or were amended but not solar heated. CONCLUSION The composition and concentration of organic matter amendments in soil significantly affected volatile fatty acid accumulation at various soil depths during biosolarization. Combining solar heating with organic matter amendment resulted in accelerated weed seed inactivation compared with either approach alone.


Applied Microbiology and Biotechnology | 2016

Enrichment of microbial communities tolerant to the ionic liquids tetrabutylphosphonium chloride and tributylethylphosphonium diethylphosphate

Sara Pace; Shannon J. Ceballos; Duff R. Harrold; Whitney Stannard; Blake A. Simmons; Steven W. Singer; Michael P. Thelen; Jean S. VanderGheynst

The aims of this study were to identify thermophilic microbial communities that degrade green waste in the presence of the ionic liquids (IL) tetrabutylphosphonium chloride and tributylethylphosphonium diethylphosphate and examine preservation methods for IL-tolerant communities. High-solids incubations with stepwise increases in IL concentration were conducted to enrich for thermophilic IL-tolerant communities that decomposed green waste. 16S rRNA sequencing of enriched communities revealed microorganisms capable of tolerating high levels of IL. Cryogenic preservation of enriched communities reduced the IL tolerance of the community and decreased the relative abundance of IL-tolerant organisms. The use of cryoprotectants did not have an effect on microbial activity on green waste of the stored community. A successful approach was developed to enrich communities that decompose green waste in thermophilic high-solids environments in the presence of IL. Alternative community storage and revival methods are necessary for maintenance and recovery of IL-tolerant communities. The enriched communities provide a targeted source of enzymes for the bioconversion of IL-pretreated green waste for conversion to biofuels.


Journal of Agricultural and Food Chemistry | 2017

Assessment of Two Solid Anaerobic Digestate Soil Amendments for Effects on Soil Quality and Biosolarization Efficacy

Jesús D. Fernández-Bayo; Yigal Achmon; Duff R. Harrold; Dlinka G. McCurry; Katie Hernandez; Ruth M. Dahlquist-Willard; James J. Stapleton; Jean S. VanderGheynst; Christopher W. Simmons

Anaerobic digestion is an organic waste bioconversion process that produces biofuel and digestates. Digestates have potential to be applied as soil amendment to improve properties for crop production including phytonutrient content and pest load. Our objective was to assess the impact of solid anaerobic digestates on weed seed inactivation and soil quality upon soil biosolarization (a pest control technique that combines solar heating and amendment-induced microbial activity). Two solid digestates from thermophilic (TD) and mesophilic (MD) digesters were tested. The solarized TD-amended samples presented significantly higher mortality of Brassica nigra (71%, P = 0.032) than its equivalent incubated at room temperature. However, biosolarization with digestate amendment led to decreased weed seed mortality in certain treatments. The plant-available water, total C, and extractable P and K were significantly increased (P < 0.05) in the incubated amended soils. The results confirm the potential of digestates as beneficial soil amendments. Further studies are needed to elucidate the impacts of digestate stability on biosolarization efficacy and soil properties.


Pest Management Science | 2018

Effect of management of organic wastes on inactivation of Brassica nigra and Fusarium oxysporum f.sp. lactucae using soil biosolarization: Managing organic wastes to improve soil biosolarization to control pests

Jesús D. Fernández-Bayo; Tara E. Randall; Duff R. Harrold; Yigal Achmon; Kelley Hestmark; Joey Su; Ruth M. Dahlquist-Willard; Thomas R. Gordon; James J. Stapleton; Jean S. VanderGheynst; Christopher W. Simmons

BACKGROUND Soil biosolarization is a promising alternative to conventional fumigation. Volatile fatty acids (VFAs) produced in the soil through fermentation of amended organic matter can affect pest inactivation during biosolarization. The objective was to determine how soil amended with organic wastes that were partially stabilized through either composting or anaerobic digestion affected the inactivation of Brassica nigra (BN; a weed) and Fusarium oxysporum f. sp. lactucae (FOL; a phytopathogenic fungus). RESULTS The mortality of BN seeds in the biosolarized soil was 12% higher than in the solarized soil, although this difference was not significant. However, a significant correlation between BN mortality and VFA accumulation was observed. The number of FOL colony-forming units (CFU) in solarized samples at 5 cm was 34 CFU g-1 of soil, whereas in the biosolarized samples levels were below the limit of quantification. At 15 cm, these levels were 100 CFU g-1 for solarized samples and < 50 CFU g-1 of soil for the biosolarized samples. Amendment addition positively affected the organic matter and potassium content after the solarization process. CONCLUSION The organic waste stabilization method can impact downstream biosolarization performance and final pest inactivation levels. This study suggests that organic waste management practices can be leveraged to improve pest control and soil quality.


Journal of Agricultural and Food Chemistry | 2018

The effects of short-term biosolarization using mature compost and industrial tomato waste amendments on the generation and persistence of biocidal soil conditions and subsequent tomato growth

Yigal Achmon; Nir Sade; Maria del Mar Rubio Wilhelmi; Jesús D. Fernández-Bayo; Duff R. Harrold; James J. Stapleton; Jean S. VanderGheynst; Eduardo Blumwald; Christopher W. Simmons

Conventional solarization and biosolarization with mature compost and tomato processing residue amendments were compared with respect to generation of pesticidal conditions and tomato ( Solanum lycopersicum L.) plant growth in treated soils. Soil oxygen depletion was examined as a response that has previously not been measured across multiple depths during biosolarization. For biosolarized soil, volatile fatty acids were found to accumulate concurrent with oxygen depletion, and the magnitude of these changes varied by soil depth. Two consecutive years of experimentation showed varying dissipation of volatile fatty acids from biosolarized soils post-treatment. When residual volatile fatty acids were detected in the biosolarized soil, fruit yield did not significantly differ from plants grown in solarized soil. However, when there was no residual volatile fatty acids in the soil at the time of planting, plants grown in biosolarized soil showed a significantly greater vegetation amount, fruit quantity, and fruit ripening than those of plants grown in solarized soil.


Process Biochemistry | 2017

Nitrogen amendment of green waste impacts microbial community, enzyme secretion and potential for lignocellulose decomposition

Chaowei Yu; Duff R. Harrold; Joshua T. Claypool; Blake A. Simmons; Steven W. Singer; Christopher W. Simmons; Jean S. VanderGheynst


Applied Soil Ecology | 2017

Comparison of soil biosolarization with mesophilic and thermophilic solid digestates on soil microbial quantity and diversity

Jesús D. Fernández-Bayo; Yigal Achmon; Duff R. Harrold; Joshua T. Claypool; Blake A. Simmons; Steven W. Singer; Ruth M. Dahlquist-Willard; James J. Stapleton; Jean S. VanderGheynst; Christopher W. Simmons


TeachEngineering Digital Library Submission Portal | 2017

Water Bottle Rockets

Duff R. Harrold; Michael Mullen; Jean S. VanderGheynst


2017 Spokane, Washington July 16 - July 19, 2017 | 2017

Effect of Partially Stabilized Organic Amendments on Volatile Acids Production and Pest Inactivation using Soil Biosolarization

Jesús D. Fernández-Bayo; Tara E. Randall; Yigal Achmon; Kelley Hestmark; Duff R. Harrold; Joey Su; Ruth M. Dahlquist-Willard; Thomas R. Gordon; James J. Stapleton; Christopher W. Simmons

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Yigal Achmon

University of California

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Blake A. Simmons

Lawrence Berkeley National Laboratory

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Joey Su

University of California

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Steven W. Singer

Lawrence Berkeley National Laboratory

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