Subsurface infiltration and surface bioretention systems composed of engineered and/or native soils are preferred tools for\r\nstormwater management. However, the disturbance of native soils, especially during the process of adding amendments to improve\r\ninfiltration rates and pollutant removal, may result in releases of nutrients in the early life of these systems. This project investigated\r\nthe nutrient release from two soils, one disturbed and one undisturbed. The disturbed soil was collected intact, but had to be airdried,\r\nand the columns repacked when soil shrinkage caused bypassing of water along the walls of the column. The undisturbed\r\nsoil was collected and used intact, with no repacking. The disturbed soil showed elevated releases of nitrogen and phosphorus\r\ncompared to the undisturbed soil for approximately 0.4 and 0.8m of runoff loading, respectively. For the undisturbed soil, the\r\nnitrogen release was delayed, indicating that the soil disturbance accelerated the release of nitrogen into a very short time period.\r\nLeaving the soil undisturbed resulted in lower but still elevated effluent nitrogen concentrations over a longer period of time. For\r\nphosphorus, these results confirm prior research which demonstrated that the soil, if shown to be phosphorus-deficient during\r\nfertility testing, can remove phosphorus from runoff even when disturbed.
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