Chemical Changes in the Soil Solution from a Spodosol Irrigated with Secondary-treated Sewage Effluent
1976
Hortenstine, C. C.
The native vegetation (Pinus elliotti, P. palustris, Quercus geminata, Serenoa repens, Aristida stricta, etc.) on 40 ha of Spodosols at Walt Disney World, near Orlando, Fla., was chopped and turned under in the winter of 1972. The following summer, three tree species (Eucalyptus robusta, Liquidambar styraciflua, Platanus occidentalis) and one grass species (Cynodon dactylon) were planted. Irrigation with secondary-treated sewage effluent at 5 cm/week was initiated in July 1972 in an attempt to determine the renovative capability of Spodosols. The soil solution was monitored chemically by drawing samples through porous ceramic cups placed at 60-, 90-, and 120-cm depths in the soil profile. Phosphorus content increased from 0.03 ppm at all depths in the fall/winter of 1971/1972 to 1.25 ppm at 60 cm, 1.00 ppm at 90 cm, and 0.85 ppm at 120 cm by fall 1974. During the same period, K increased from 0.05 ppm at all three depths to 14 ppm; however, NO₃-N was consistently below 1.0 ppm. The effluent contained an average of 2.2 ppm NO₃-N, 14 ppm Kjeldahl N, 2.8 ppm P, and 16 ppm K. Laboratory tests of the soil indicated satisfactory nitrification; however, adverse conditions in the field probably curtailed the nitrifying process.
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