nutrients & agrichemicals (24)

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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27 Apr 2020

Clean up your Water with Carbon Filtration

Paul Fisher, George Grant (University of Florida), and Rosa Raudales (University of Connecticut)

Are pesticide residues iin your irrigation water suppressing crop growth or causing phytotoxicity? Agrichemicals in water can be an issue in several situations. Persistent chemicals can accumulate in recirculation systems and affect subsequent crops even in the parts per billion (ppb) range. Growers using pond water occasionally experience a problem when herbicides are applied to surrounding land in the water shed and crop growth is suddenly deformed. Filtration using granular activated carbon in most cases is the best solution to remove pesticides from water. This article provides guidelines on design and operation of a GAC filter for greenhouses and nurseries.

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6 Jan 2020

Water Conserving Irrigation Practices, Plant Growth, Seasonal Crop Coefficients, and Nutrition of Container-Grown Woody Ornamentals

R. Thomas Fernandez, Nicholas A. Pershey, Jeffrey A. Andresen, and Bert M. Cregg (Michigan State University)

Container nursery irrigation practices often result in over-application leading to nutrient leaching and reduced growth. Our objectives were to compare growth and foliar nutrient content for plants under control (19 mm or ¾ inch daily) and 3 daily water use (DWU) based irrigation treatments; determine DWU of 14 woody plants; and classify plants into irrigation groups. Average DWU ranged between 2.1 and 22.0 mm. Most DWU-based treatments resulted in less water applied than the control, yet plant growth was not reduced. Lower foliar P and K concentrations were found for several taxa in control versus DWU treatments.

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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.