Nitrate Transformations in a Column with a Controlled Water Table

Abstract

The relation of dissolved oxygen, soluble carbon, and redox potential to the movement of nitrate in soil columns and into submerged tile lines was studied. Columns 300 cm long were drained at depths of 180, 240, or 300 cm with the water table in all columns maintained at 175 cm. After adding ammonium nitrate and irrigating, the peak in nitrate concentration moved downward to the 160‐cm depth, but nitrate concentrations decreased at 180 cm and almost disappeared at the 240‐ and 300‐cm depths. The soil solution at 180 cm contained an average of 5.2 ppm nitrate‐nitrogen and a maximum of 16 ppm. In contrast the soil solution at 240 or 300 cm, which had passed through a submerged zone of 65 or 125 cm, averaged 0.5 ppm and had a maximum concentration of 1.1 ppm. Disappearance of nitrate was associated with decreases in redox potential, oxygen content of the soil solution and oxygen levels in the soil atmosphere, and with increases in soluble iron and manganese. Denitrification occurred without submergence if the soil redox potential was sufficiently low. Results of this experiment indicate that nitrate concentrations probably can be reduced in tile effluents by submerging the tile lines.

Nutrient loss from disturbed forest watersheds in Oregon's coast range

“…collections. Decreasing nitrate wii.h increasing depth had been documented in saturated lower profiles by Meek et al (1969Meek et al ( , 1970. Bicarbonate increased (cu = 0.01) with depth, presumably because of increased COz partial pressures (Boynton and Compton, 1944;McCall and Cole, 196S).…”

Biochemical Ecology of Nitrification and Denitrification

“…In the two soils that were tested, they calculated that more than sufficient soluble organic matter was leached with the nitrate to this zone to effect complete reduction of the nitrate. Similarly, Meek et al (1970) presented evidence of a continual drop in the redox potential from the surface to a 2 m depth at the tile drain. They showed that sufficient organic matter was leached with the drainage water to eventually reduce almost all of the nitrate throughout the profile.…”

Arsenic release and speciation in a degraded fen as affected by soil redox potential at varied moisture regime

“…Meek et al (1970) and Mansfeldt (2004 concentrations observed in the A and Ag horizons at the end of the unsaturated period (10 kPa pressure head step) may be the result of sample pre-treatment. Homogenization and air drying of the soil are likely to have promoted mineralization of organic N sources and caused the NO 3 − peak under unsaturated conditions.…”