nutrients & agrichemicals (9)

28 Sep 2016

Remediating Paclobutrazol From Irrigation Water Using Activated Carbon

Grant, G.A., Fisher, P., Barrett, J.E., Wilson, C.P. (University of Florida)

Recirculating irrigation water can sometimes have residual agrichemicals present, such as paclobutrazol.  Paclobutrazol is an active ingredient used in plant growth regulators to control plant height.  The objective of this project was to use granular activated carbon filtration (GAC) to remove paclobutrazol using different contact times.  A 0.05 mg·L-1 (50ppb) paclobutrazol solution was passed through a small-scale, 0.50 to 4.75 mm particle size (8x30 mesh) coconut coir GAC system.  A bioassay of broccoli seeds and begonia seedlings were used to show the effect of before and post GAC filtered water.  Paclobutrazol concentration decreased by 90% or 99% with a contact time of 12 seconds or 59 seconds GAC, respectively. Overall, this experiment showed that granular activated carbon has the potential to remediate paclobutrazol from irrigation water to below biologically-active concentrations.

ASHS Abstract 2016 Grant (270 KB)

14 Sep 2016

When to Fertigate: The Influence of Substrate Moisture Content on Nutrient Retention in Containerized Crop Production

McPherson, S., Owen, J.S., Brindley, J., Fields, J.S. (Virginia Tech)

The efficient use of fertilizers is key to increase profitability for the agriculture industry (nursery and greenhouse).  Fertigation efficiency increased as pine bark substrate moisture increased (38% to 56% gravimetrically).  It was hypothesized that mineral retention occured with uniformly distributed water.   

SNA Research Conference Vol. 60 2015

SNA When to fertigate (179 KB)

1 Jun 2016

Nutrient Remediation using Two Plant Species in a Floating Treatment Wetland System

Garcia, L.M., Majsztrik, J.C., Bell, N.L., White, S.A. (Clemson University)

Excess nutrients are often present in production runoff from nurseries and greenhouses because fertilizers are used to grow plants. In 2015, we conducted trials with floating treatment wetlands (FTWs) to determine how much nutrients soft rush (Juncus effusus) and pickerelweed (Pontederia cordata) could absorb.  When harvested after 20 weeks, with pond nutrient concentrations averaging 10 ppm N and 3 ppm P, a 1-acre are of planted FTWs would remove 88 lbs. of N and 15 lbs. of P if planted with soft rush or 1,320 lbs. of N and 255 lbs. of P if planted with pickerelweed.

ASHS Abstract (78 KB)     ASHS Presentation (774 KB)

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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.