Water Resources Research Center, University of Minnesota
Newsletter or Bulletin
During 1980, septage was applied in rates of 1120 and 1500 kg of
nitrogen per hectare to three different soil textures in an attempt
to determine maximum loading rates. These rates resulted in increased concentrations
of nitrates in the soil water for a Hubbard loamy Sanci, Waukegan silt loam and Lester clay loam, indicating that the application
rates exceeded the maximum rate that the soils could treat.
The first year's results indicate that soil type, application rates and
soil depth resulted in no significant difference in total Kjeldahl nitrogen,
ammonia, fecal streptococcus and fecal coliforms in the soil water
samples. Nitrate concentrations, however, were significantly different
between the soils, application rates and soil depths. For the Hubbard
loamy sand, rainfall had a larger effect on nitrate concentrations and
movement within the soil profile than for the Waukegan silt loam or Lester
clay 1oam. 0n the Waukegan silt loam and Lester clay loam there was relatively
little change in the nitrate concentration in the soil profile
during the period when septage was applied twice a week.
After the design loading had been applied to the soil and no further
applications made, a sharp increase in nitrate concentrations was observed
in the soil profile. This probably resulted from changing the anaerobic
surface layer to an aerobic condition resulting in nitrification and subsequent
movement of nitrates through the profile following a rainfall event. With no additional septage application, the second year's data indicate
a significant difference in nitrate-N between soils, application rates, and
depths. Generally, the nitrate concentrations in the Hubbard loamy sand
and Waukegan silt loam were less than the first year, but the concentrations
in the Lester clay loam were higher than the first year. This
indicates that nitrification and nitrate movement in the Lester clay loam
are slower than the other two soils.
Application resulted in a significant increase in the concentration of
soil water calcium, magnesium, sodium and potassium during the first year
of the study. However, there was no increase in the phosphorus content of
the soil water.
Anderson, J.L. Clanton, C.J. Hansel, M.J. Machmeier, R.E. 1983. Maximum Application Rates for Land Treatment of Septage. Water Resources Research Center.
Water Resources Research Center
Anderson, James L.; Clanton, C.J.; Hansel, M.J.; Machmeier, R.E..
Maximum Application Rates for Land Treatment of Septage.
Water Resources Research Center, University of Minnesota.
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