Nitrification and Denitrification near a Soil–Manure Interface Studied with a Nitrate-Nitrite Biosensor
- Rikke Louise Meyer *,
- Thomas Kjær and
- Niels Peter Revsbech
A two-layer system of cattle (Bos taurus) manure and soil was used to study the development of nitrification and denitrification processes associated with the oxic–anoxic interface of soil and manure over a period of 18 d. By use of microsensors, depth profiles of O2 and nitrate plus nitrite NO− x were measured. We observed an initial depletion of NO− x originally present in the soil, followed by an increase after ∼1 wk caused by the activity of nitrifying bacteria. Fluxes of NO− x from the soil into the manure were calculated from NO− x profiles and compared with measurements of N2 production. Generally, NO− x fluxes and N2 production were concordant. Denitrification (NO− x consumption) was closely coupled to nitrification until Day 18, when NO− x accumulated in the anoxic zone and therefore no longer seemed to limit denitrification. Maximum denitrification rates were measured at Day 9/10 and reached 732 and 497 nmol N m−2 h−1 when measured as NO− x flux and N2 production, respectively. An experiment was set up to investigate the temporal change in NO− x profiles when nitrification was inhibited by acetylene. Profiles of NO− x were measured at 0, 2, 4, 8, 16, 24, and 48 h of incubation with 1% acetylene. Calculated NO− x fluxes were 39% of the original rates after 2 h and only 2% after 48 h. Thus, this experiment stresses the importance of very short incubation time when using the acetylene inhibition technique to measure denitrification rates.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2002.