Presented by

Cynthia M. Hill

Ph.D. Candidate Crop & Soil Sciences

Tuesday, April 25, 2000
3:30-4:30 PM
135 Emerson Hall

Abstract

While constructed wetlands can be a cost-effective method for reducing the export of P from agricultural ecosystems, removal rates vary widely. The objective of this research was to evaluate substrates that could consistently improve P treatment in these wetlands. We built eight 55 sq m subsurface wetland cells on an 800-head dairy farm in Newark, NY, USA, to test alternative substrates for removing soluble P from dairy barnyard runoff. The four media were (1) a fine loamy, mixed, mesic Glossic Hapludalf, (2) crushed limestone, (3) Norlite, lightweight coarse aggregates of fired shale, and (4) calcium metasilicate mining tailings with a limestone prefilter. Based on this research, we recommend Norlite for P removal in agricultural ecosystems. The native soil retained more soluble P but could not sustain subsurface flow. Calcium metasilicate tailings warrant further research. They adsorbed 2 mg P/g in the laboratory but performed less well in the field, probably because of preferential flow