Nitrogen Mobility in Biosolid-Amended Glaciated Soil

Abstract

The potential leaching and availability of nitrogen in biosolids and biosolid-amended glaciated soil were investigated using mineralization and column studies. Aerobic and anaerobic mineralization studies were conducted to assess nitrogen mineralization potential from biosolid-amended glaciated soils and estimate long- and short-term mineralization rates of products. Semicontinuous column studies were conducted to assess the leachability of nitrogen from biosolid-amended soil under simulated unsaturated soil conditions. This study used a Paxton soil because its characteristics are typical of glaciated soil found in New England. Three types of biosolids, which are representative of biosolids currently available in Connecticut, were evaluated: composted biosolids (compost), cement kiln dust stabilized (CKD) biosolids, and heat-dried biosolids (pellet). Results indicate that the pellet product had the greatest mineralization potential (based on unmixed biosolids) at 5 317 mg N/kg, followed by compost (324 mg N/kg) and CKD biosolids (58 mg N/kg). Nitrogen mineralized for the anaerobic test (mixed with soil) varied from 56 to 90% of the total nitrogen and for the aerobic test varied from 19 to 57%. The CKD biosolids percolate consisted primarily of nitrate and nitrite, whereas the predominant nitrogen species found in compost and pellet biosolids percolate was ammonium. Results suggest that one-time application of biosolids at agronomic or liming rates (whichever is limiting) will cause minimal effects to groundwater.