Denitrification rhizosphere

Kronzucker et al. (1999, 2000) have found that lowland rice (cv IR72) grown hydroponically is exceptionally efficient in absorbing NOs", raising the possibility that rice growing in flooded soil may absorb significant amounts of NO3 formed by nitrification of NH4+ in the rhizosphere. This is important because (a) this NO3 is otherwise lost through denitrification in the soil bulk (Reddy... 

Risgaard-Petersen, N., andjensen, K. (1997). Nitrification and denitrification in the rhizosphere of the aquatic macrophyte Lobelia dortmanna (L.). Limnol. Oceanogr. 42, 529—537. 

Ottosen, L. D. M., Risgaard-Petersen, N., and Nielsen, L. P. (1999). Direct and indirect measurements of nitrification and denitrification in the rhizosphere of aquatic macrophytes. Aquat. Microb. Ecol. 19, 81-91. 

Arth, I., Frenzel, P., and Conrad, R. (1998). Denitrification coupled to nitrification in the rhizosphere of rice. Soil Biol and Biochemi. 30, 509-515. 

Nitrification-denitrification reactions are the major pathway for N loss from wetland ecosystems to the atmosphere. The process involves a series of sequential microbial processes that include mineralization of organic nitrogen to ammonium, oxidation of ammonium to nitrate, and denitrification of nitrate to nitrous oxide or dinitrogen gas. Nitrification-denitrification in wetlands occurs primarily in two zones the aerobic-anaerobic interface at the surface of the flooded soil or sediment, and the oxidized rhizosphere of wetland plants (Figure 16.6). 

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