Carbon and nitrogen losses from undisturbed soil columns under short- term flooding conditions

Abstract

After 8 wk of incubation, the amounts of soluble organic carbon leached by 0.001 M CaCl2 solution from flooded soils ranged from 153 to 630 mg C kg-1. In contrast, only 28-107 mg C kg-1 was leached from nonflooded soils. The amounts of soluble organic nitrogen leached from the flooded soils ranged from 10 to 30 mg N kg-1 compared with 5.9-12 mg N kg-1 from nonflooded soils. In the flooded soils, ammonium nitrogen dominated the total inorganic nitrogen leached (99.5-99.9%) whereas in nonflooded soils leachable N was mainly nitrate and nitrite (97.4-99.9%). Methane was emitted from the flooded soils (10-138 mg C kg-1 over 8 wk). The rate of carbon dioxide evolution in flooded soils increased linearly with time and total evolution ranged from 72 to 552 mg C kg-1, whereas CO2 evolution in the nonflooded soils was steady with total evolution ranging from 159 to 1279 mg C kg-1 after 8 wk. -from Authors