Field experiments were established at two locations (on an Oxisol and
an Ultisol) to evaluate the effects of 0, 8, 16, and 24 metric tons ha
-1 of aged municipal sewage sludge on soil properties and growth of fo
ur crop species. Soil samples taken from each plot, before sludge appl
ication and at harvest of the crops, are compared here to determine an
y effects of the sludge on pH, exchangeable acidity, exchangeable base
s, cation and anion exchange capacity, and extractable phosphorus and
trace metals. To test effects on soil properties in a more controlled
environment, soil from one site was incubated with the sludge over a p
eriod of 4 months. No detrimental effects and several beneficial effec
ts were observed. In particular, problems of soil acidity were diminis
hed by an increase in pH and exchangeable calcium accompanied by a dec
rease in exchangeable acidity. Sludge applications also increased BaCl
2-MgS64 CEC, but only in the Oxisol did the sum of cations increase. D
ilute acid-fluoride extractable phosphorus also increased with sludge
additions accounting for 2 to 19% of added sludge P for the Ultisol an
d 19 to 52% of P added to the Oxisol. Increases in Mehlich-3 extractab
le Cu and Zn in the soils were approximately equal to the amounts of t
hese elements added to the soil in the sludge.