Nitrate Leaching in a Sludge-Treated Forest Soil
1979
Sidle, R. C. | Kardos, Louis T.
Anaerobically digested liquid sludge was applied during two separate periods to plots in a mixed hardwood forest. High treatment plots received 26.96 metric tons/ha total solids and 3,034 kg/ha N loadings during the two applications, and low treatment plots received approximately half these loadings. Percolate samples collected at the 15-cm depth contained a maximum of 290 mg/liter NO₃⁻-N in the high treatment and 194 mg/liter NO₃⁻-N in the low treatment. Maximum monthly levels of NO₃⁻-N in percolate sampled at the 120-cm depth lagged 6 months behind peak levels at the 15-cm depth. Calculated average active transmitting soil porosity (Pₐcₜ), based on field water budget data over this 6-month period, ranged from 15 to 22%. A CSMP computer simulation model based on a solution to the convection diffusion equation estimated the average Pₐcₜ to be 15%. Since these data indicate that 27 to 50% of the pores may be stagnant, this suggests that soluble NO₃⁻-N was being channeled through interconnected macropores in the soil profile.
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