Distribution of fertiliser N among fixed ammonium fractions as affected by moisture and fertiliser source and rate
2007
Gouveia, Gregory A. | Eudoxie, Gaius D.
The relevance of fixed [graphic removed] in certain soils and its categorisation has made it necessary to re-examine N behaviour. A replicate factorial experiment was designed to investigate the influence of soil type, soil moisture and fertiliser source and rate on [graphic removed] fixation dynamics with particular attention to the distribution between weakly and strongly fixed pools. Fixation of [graphic removed] was <20% of added N for all soils except River Estate. The percentage of added N present as fixed [graphic removed] was greater for the low application rate. Soil moisture did not significantly influence weakly fixed [graphic removed] . However, the dry soil treatment showed greater fertiliser ¹⁵N present as strongly fixed [graphic removed] . Fertiliser ¹⁵N present as weakly and strongly fixed [graphic removed] decreased and increased, respectively, at the second sampling, indicating movement between the pools. The importance of the weakly fixed [graphic removed] fraction as a transitory pool between strongly fixed [graphic removed] and available [graphic removed] was observed.
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