Most recent

12 Oct 2020

Water and air relations in propagation substrates

Erin J. Yafuso, Paul R. Fisher, Ana C. Bohórquez (University of Florida), and James E. Altland (USDA-ARS)

Greenhouse propagation of unrooted plant cuttings is characterized by short container cell height and high irrigation frequency. These conditions can result in high moisture level and low air content in soilless container substrates, causing delayed growth of adventitious roots and favoring root disease. The objective of this study was to quantify and compare substrate water and air relations for three propagation substrates (peat, rockwool, and phenolic foam).

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10 Aug 2020

Nutrient and pesticide remediation using a two-stage bioreactor-adsorptive system under two hydraulic retention times

Damon E. Abdi, James S. Owen Jr, Julie C. Brindley, Anna C. Birnbaum, P. Chris Wilson, Francisca O. Hinza, Gemma Reguera, Joo-Young Lee, Bert M. Cregg, Daniel R. Kort, R. Thomas Fernandez

Nutrients and pesticides in irrigation return flow from agricultural operations pose an environmental risk. Water treatment systems, such as woodchip bioreactors and expanded aggregate filters, can be used to remediate these contaminants. Our objectives were to investigate agrochemical removal with these systems when operated under an extended hydraulic retention time (HRT) of 3 days and a rapid HRT of 21 minutes. A 3 day HRT effectively reduced nitrate and phosphate below 0.2 ppm in woodchip bioreactors and expanded shale filters, respectively; while a 21 minute HRT was sufficient for removing 50-75% of influent pesticide content but not for nutrient removal. 

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Description of research activities

A national team of scientists is working to encourage use of alternative water resources by the nation’s billion-dollar nursery and floriculture industry has been awarded funds for the first year of an $8.7 million, five year US Department of Agriculture – National Institute of Food and Agriculture –Specialty Crop Research Initiative competitive grant.

The team will develop and apply systems-based solutions to assist grower decision making by providing science-based information to increase use of recycled water.  This award from the NIFA’s Specialty Crop Research Initiative is managed by Project Director Sarah White of Clemson University.  She leads a group of 21 scientists from nine U.S. institutions.

Entitled “Clean WateR3 - Reduce, Remediate, Recycle – Enhancing Alternative Water Resources Availability and Use to Increase Profitability in Specialty Crops”, the Clean WateR3 team will assist the grower decision-making process by providing science-based information on nutrient, pathogen, and pesticide fate in recycled water both before and after treatment, average cost and return-on investment of technologies examined, and model-derived, site specific recommendations for water management.  The trans-disciplinary Clean WateR3 team will develop these systems-based solutions by integrating sociological, economic, modeling, and biological data into a user-friendly decision-support system intended to inform and direct our stakeholders’ water management decision-making process.

The Clean WateR3 grant team is working with a stakeholder group of greenhouse and nursery growers throughout the United States.

For example, at the University of Florida graduate student George Grant is collecting data on removal of paclobutrazol, a highly persistent plant growth regulator chemical, from recirculated water using granular activated carbon (GAC) filters. This is being done in both research greenhouses and in a commercial site. The GAC filters can remove more than 90% of chemical residues, and are proving to be a cost-effective treatment method.