Municipal Sewage Sludge and Selected Element Applications to Soil: Effect on Soil and Fescue
1975
Boswell, F. C.
Effects of additions of sewage sludge from a highly industrialized area of Atlanta, Georgia, N-P-K inorganic fertilizers, selected heavy metals, and trace elements were made on 3 by 9 m plastic-divided plots sodded to fescue (Festuca arundinacea Schreb.) to evaluate accumulations and movement patterns in the soil. Fescue yields and elemental content were also determined. Soil samples taken 17 weeks after the initial sludge treatment showed only slight increases in Cd, Cr, Cu, Pb, and Zn content. One year later (72 weeks after the initial treatment), two additional applications of sewage sludge (a total of 16.8 metric tons/ha had increased the levels of these elements in the surface 7.5-cm soil layer approximately 7, 3, 4, 4, and 5 times, respectively. The Zn content was the highest (88 ppm), followed by Pb (12 ppm), Cu (3.2 ppm), Cr (2.0 ppm), and Cd (1.4 ppm). Adding selected elements to the sewage sludge, even at relatively high levels, resulted in little movement of Zn lower than 30 cm and other heavy metals lower than 15 cm. Forage yields over the 2-year period were increased, over control plots, approximately 30% by the sewage sludge and 150% by N-P-K fertilizer. The sewage sludge additions significantly increased the heavy metal and P contents in fescue, but not of K, Ca, and Mg. The greatest increase was from 33 to 1,419 ppm of Zn as an average of 8 sampling periods. No toxic or detrimental effects on fescue were noted.
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