Determination of Optimum Tree Density and Biosolid Application Rate and the Effect on Water Quality and Tree Growth Using the Deep Row Biosolids Incorporation Method

The PI’s are Jonathan Kays, Dr. Gary Felton and Erik Flamino. The sponsor is Washington Suburban Sanitary Commission and funded at $255,000. The duration of this project is January 2005 – December 2008.

Description: Deep-row application of biosolids on reclamation sites is a unique alternative land application method that solves many of the problems associated with surface application techniques. When combined with the growth of nitrogen-demanding hybrid poplar trees, it provides a natural recycling system that utilizes nutrients on-site, produces forest products, generates wildlife habitat, and reduces erosion while reclaiming abandoned, biologically sterile soils created by sand and gravel surface mining operations.

This project applied biosolids at 3 rates (6,000, 12,000, and 18,000 lbs nitrogen/acre) to grow hybrid poplar trees for a six year cycle at 10’ x 10’ and 10’ x 17’ spacing. Water quality measurements were collected to define nutrient fate and transport. Extension education aimed at regulators and legislative aids have been delivered. The ERCO Beneficial Reuse Tree Farm site is a privately-owned 49.4 ha. (122 ac.) sand and gravel mine spoil in Prince George’s County, MD within 40 km (25 miles) of many large municipal wastewater treatment plants. After 24 years of monitoring eight wells, no sample even approaches the 10 mg N/L limit for nitrate nitrogen and in fact, only one sample even exceeds a concentration that is one-tenth of the standard.

For more information, contact Jonathan Kays

Last updated: 02/6/2008