The The Baltimore/Washington, D.C.
Metro area produces about 1.2 million wet tons of biosolids per
year from area treatment plants (2002 figures). While much of this
material has been applied to agricultural fields in the past or
sent out of state, new regulations and the loss of agricultural
land to development have required investigating other beneficial
uses of biosolids.
Application to native forests has been the dominant use of biosolids
since 1987 in King County, Washington, which includes the Pacific
Northwest cities of Seattle and Tacoma. Their website, Fertilizing
Forests With Biosolids details their program and the positive
impacts on forests. Many citizens have negative perceptions and
concerns about forest application of biosolids that include those
related to health and safety, but these concerns have been addressed
in King County by sound education and decades of experience. It
is an education approach that should be used with new projects.
The forest land base and the higher population pressures in the
Mid-Atlantic area make application of biosolids to native forests
more challenging. However, the development of specially designed
forest plantations that are engineered to use biosolids as their
nutrient base is an approach that has worked well in British Columbia,
Canada, and Washington State, and holds promise for our area. The
tree of choice is hybrid poplar, a clonal species that is developed
from crosses of native cottonwood species, and has the ability to
utilize very high amounts of nitrogen and other nutrients. Hybrid
poplar-biosolids forest plantation systems hold great promise for
utilizing biosolids in high amounts, while producing woody biomass
that has utility for many uses.
The Mid-Atlantic Biosolids
Association is a professional organization comprised of utilities,
businesses and non-government committed to good management of biosolids
in the six states of New York, New Jersey, Pennsylvania, Delaware,
Maryland and Virginia. Check out their website for what is happening
with the use of hybrid poplar-biosolids systems.
Deep Row Incorporation of Biosolids with
Hybrid Poplar
A promising technique that utilizes high application rates of biosolids
to grow hybrid poplar trees planted on abandoned gravel spoils in
southern Maryland is called deep row incorporation with forest
trees. Deep row refers to the application of the biosolids in
a trench which is immediately covered, eliminating odors and slowing
the mineralization process that affects water quality. Hybrid poplar
trees are uniquely adapted to this application technique because
of their ability to take up large amounts of nitrogen in a short
period of time.
Deep row application to grow hybrid poplar trees on gravel spoils
is a unique and innovative beneficial-use technique for applying
biosolids that solves many of the conventional application problems.
The technique has been developed on 49.4 ha (122 ac) site in the
Washington, D.C. metro area since 1983 by a private company, ERCO,
Inc.
Since 2001, the University of Maryland College of Agriculture and
Natural Resources has entered into a public private collaboration
with the Washington Suburban Sanitary Commission (WSSC) and ERCO,
Inc., a private company. Intensive research has been combined with
long-term monitoring data to develop a better understanding of water
quality impacts, operational methods, clonal selection, hybrid poplar
growth and nutrition, and the factors affecting economics and profitability.
There are no indications of nitrate leaching and the tree plantation
systems are performing well. Given the large acreage of gravel spoils
in the metro area, deep row application has the potential to utilize
significant amounts of biosolids produced in the region.
Publications
Fact Sheets
Use of Deep-Row Biosolid Applications
to Grow Forest Trees
Three Year Report from January 1, 2002 to December 31, 2004Determination of Optimum Tree Density,
Biosolid Application Rate, Water Quality Impacts and Tree
Growth Effects Using the Deep Row Biosolids Incorporation
Method. (Three year research project report.)
Annual Report for Period of July 1, 2006 – June 30, 2007 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
Kays,
J. S. (1999). Deep-Row Application of Biosolids to Grow Forest
Crops on Mine Spoils: Potential Utilization for the Baltimore,
MD - Washington, D.C. Metro Area. In Proceedings of the Water
Environment Federation/Association of Wastewater Operators Joint
Residuals and Biosolids Management Conference. January 27-30,
1999. Charlotte, NC: Water Environment Research Federation.
Kays, J. S., E. J. Flamino, G.
Felton, & P. D. Flamino. (2000). Use of deep-row biosolids
applications to grow forest trees: a case study. In C.L. Henry,
R.B. Harrison, and R.K. Bastian (Eds.), The Forest Alternative:
Principles and Practice of Residuals Use. (pp. 105-110). Seattle,
WA: University of Washington College of Forest Resources.
Buswell, C. U., G. K. Felton,
J. S. Kays, and E. J. Flamino. (2006). Water Quality of Deep Row
Biosolids Incorporation on a Tree Farm. In Proceedings of the
2006 American Society of Agricultural and Biological Engineers
Conference, July 9-12, 2006. Portland, OR.
Kays, J. S, G. K. Felton,
C. U. Buswell, and E. J. Flamino. (2007). Deep Row Incorporation
of Biosolids to Grow Hybrid Poplar Trees on Gravel Spoils in Southern
Maryland. Water Practice, Volume 1, Issue 1.
Felton, G.K., D. Maimone, and J.S. Kays. (2008). Nitrogen migration from deep-row biosolids incorporation on a hybrid poplar tree farm. NABEC Paper: 08-051 presented at 2008 NABEC annual meeting, Aberdeen, MD. 35 pp., July 28 - 30, 2008.
Address the science of reclamation of sand and gravel sites
through the use of deep row application of biosolids followed by
the planting of hybrid poplar trees to utilize the nutrients in
the biosolids over a 6-8 year rotation. Deep row application involves
applying biosolids in regularly-spaced trenches that are immediately
covered, eliminating odors and minimizing the mineralizing of nitrogen
until tree roots provide the oxygen needed for mineralization to
occur.
Use different application rates of biosolids and tree densities
to determine the impact on water quality and tree production and
other variables over a 3-year period and beyond.
Provide scientific confirmation that deep row application
with trees is a viable alternative on other gravel mine spoils in
the Washington, D.C. metro area that lie close to treatment facilities.
Use natural ecological processes to utilize biosolids in
a manner that minimizes odors, water quality impacts, and transport
problems, while providing environmental benefits from improved wildlife
habitat, and soil improvement on sites with nutritionally dead soils.
Educational Programs
