ISSN:
1432-0789
Keywords:
Key words Ammonium fixation
;
Rice paddy soil
;
Nitrogen transformation
;
Aseptic incubation
;
Wetland rice
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract An incubation experiment under aseptic and septic conditions using 15N-labelled NH4 +-N and NO3 –-N, was carried out to study the effect of N transformations after flooding on NH4 + fixation in a paddy soil from China. After flooding ammonification was favoured, providing NH4 + for fixation by clay minerals. NH4 + fixation was more pronounced under low redox potential (Eh) conditions. Close correlations existed between exchangeable NH4 +, Eh, and non-exchangeable NH4 +. Therefore, two major conditions for NH4 + fixation induced by flooding in paddy soil were found, namely flooding promoted net production of NH4 + due to the deamination of organic N and, in addition, decreased the Eh of the soil. A lower Eh was caused by reduction and dissolution of Fe oxide coating on the clay minerals' surfaces, eliminating the obstacles for NH4 + diffusing into or out of the interlayers of clay minerals. A higher concentration of exchangeable NH4 + from deamination of organic N would drive NH4 + diffusing from the soil solution into the interlayers of clay minerals. 15N-labelled NO3 – incorporated into the flooded soil was not reduced to NH3. The addition of NO3 – retarded the decrease in the soil Eh and, therefore, NH4 + fixation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s003740000202
