This paper reports the use of electromagnetic (EM) instrumentation for
surveying agronomic and waste treatment sites at locations previously
profiled by soil coring for evaluation of nutrients in the soil profi
le. Surveys were made using a geophysical EM instrument capable of mea
suring conductivity 3 to 6 m below the surface of the ground with hori
zontal or vertical polarization. Two specific sites were analyzed to e
valuate the effects of management practices: (i) An animal waste compo
sting site with one section in use since 1985 and with expanded operat
ion to another section in 1989 and (ii) A waste storage pond (operatio
nal in 1973) holding precipitation runoff from a cattle feedlot. Corre
lation analysis between the EM conductivity measurements and chemical
analysis at both sites (concentrations of NH4+, NO3-, CL-, and P) show
significant (P < 0.05) correlations for the ions while P did not show
a significant correlation. The Ehl measures were able to distinguish
the 6-yr-old site from the 10-yr-old site (P < 0.05). The results indi
cate that EM methods provide useful information for shallow subsurface
surveys of livestock waste management facilities.