A Novel Phosphate Sorbent to Reduce Non-point Source Pollution and Increase Plant Production

View the project final report

Commodities

Practices

• Crop Production: fertigation, fertilizers, greenhouses, nurseries
• Education and Training: demonstration

1) Problem, Novel Approach and Justification.
Nutrients in runoff from agricultural enterprises are a major cause of eutrophication to aquatic systems. Agricultural operations that release large amounts of nutrients are under pressure to construct large silos and/or retention ponds to collect, store and treat nutrient-laden wastes. Additionally, where these wastes have been land applied, agricultural lands may become saturated with phosphate with the excess exported to aquatic systems. Acid mine drainage (AMD) precipitates are powerful sorbents of phosphate and can be used as an engineering practice to reduce nutrient loads to the environment. We have developed a process by which selective AMD precipitates (iron and/or aluminum) can be used to coat sand. The coated sand can be placed to intercept nutrient-laden wastes in horticulture, and be incorporated into potting media to help retain phosphate and serve as an on-demand phosphate source.

2) Hypothesis and Research Plan.
Coated sand, made from AMD, is a cost-effective phosphate sorbent that allows the capture and reuse of dissolved phosphate in the greenhouse/nursery industries. This will result in reduction in fertilizer application and non-point source phosphate inputs to aquatic systems while reducing the amount of AMD sludge to be disposed of. We will use field-collected AMD water and the developed procedure to produce AMD-coated sand and use that sand in the research tasks designed to 1) evaluate if heavy metals sorb to the coating material and release to the leachate; 2) characterize AMD-coated sand’s phosphate retention capacity and phosphate export reduction; 3) evaluate the benefits of using AMD-coated sand as an amendment for potting media and determine the optimal ratio for plant growth; 4) field test the coated sand for greenhouse and nursery crop productions; and 5) introduce the AMD-coated sand in commercial greenhouse operation.

3) Outreach Plan.
A presentation will be made at the annual WV Small Farms Conference in February during years 1 and 2 to both educate as well as receive feedback regarding other ways that coated sand might be applied. Additionally, a presentation will be made at the annual meeting of the American Society for Horticultural Science. We will continue to work with both growers and the fertilizer industry who have direct contact with many growers. They will provide a direct link to growers who would be interested in adopting this technology.

1. Determine if heavy metals present in some AMD sources would be incorporated into the coating and characterize their leaching potential;
2. Determine the operational parameters for the use of coated sand in the horticultural industry; and
3. Quantify any additional benefits from using coated sand in potting media such as improved root structure, increased flowering and improved post-production success.