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Nitrate Leaching During Long‐term Spray Irrigation for Treatment of Secondary Sewage Effluent on Woodland Sites
Author(s) -
Hook J. E.,
Kardos L. T.
Publication year - 1978
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1978.00472425000700010006x
Subject(s) - effluent , irrigation , environmental science , loam , nitrate , leaching (pedology) , soil water , hydrology (agriculture) , agronomy , environmental engineering , chemistry , soil science , geology , geotechnical engineering , organic chemistry , biology
Two waste water‐treated sites at The Pennsylvania State University Wastewater Renovation Project were monitored to measure nitrate and total N in soil water. Both long‐term waste water irrigation and varied irrigation rates were examined. Soil water was sampled by porous cup samplers. The concentration of N at the 120‐cm depth was taken as a measure of N which escaped the root zone and which would leach to the ground water. Recharge volume was calculated from irrigation, rainfall, and potential evapotranspiration. A hardwood forest site located on a well‐drained sandy loam soil was irrigated year round with secondary municipal effluent at a rate of 5 cm/week. In the last 6 of 9 years of effluent treatment 83% of the 4,954 kg N/ha added leached from the site. Nitrate concentration in soil water at the 120‐cm depth was generally > 15 mg N/liter. The hardwood forest was also ineffective in keeping nitrate concentration below 10 mg N/liter at the 120‐cm depth when the 5‐cm weekly application was split into two 2.5‐cm irrigations or when it was lowered to 2.5 cm/week year round. An abandoned old field site planted with white spruce ( Picea glauca Moench) and located on a well‐drained clay loam soil was irrigated with effluent at 5 cm/week from Apr. through Nov. each year, beginning in 1963. Nitrate concentration at the 120‐cm depth rarely exceeded 10 mg N/liter and only 36% of the 1,246 kg N/ha applied leached during the 6th through the 9th years of this effluent treatment. In the 10th and 11th years, when the application rate was increased to 7.5 cm/week, nitrate concentration exceeded 10 mg N/liter at the 120‐cm depth, and the amount of N which leached increased to 75% of the amount applied.