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Two mathematical models were used to predict the
nitrification rate of Taiwan soil in this study. One was
using the multiple factors'' regression equation of
nitrification parameter(Laubscher ,1990) and the nitrification
equation to predict nitrification rate of the soil whose
properties, environmental conditions and nitrifier population
were known. The results showed that this model got a good
predict value ( R square 0.92 in Taichung soil). But there were
eight factors needed to be measured in this model. Therefore,
the other model was only using the population of nitri- fiers
multiplying the nitrification rate per cell to estimate the
soil nitrification rate. The results showed that the
population of nitrite oxidizer multiple the nitrification
rate per cell could estimate the nitrification rate and
could be used as an indicator of nitrogen pollution of
chemical fertilizer in soils. Stepwise regression analysis
was used to identify the factors regulating nitrification and
regression equations were used to quantatively describe the
factors regulating the nitrification parameters. The former
showed that the factors regulating the maximal
nitrification rate were the population of autotrophic
ammonia oxidizer, the initial ammonium concerntration,
water tension and cation exchange capacity of soils. The
latter showed that the maximal nitrification rate positively
correlated with initial ammoniumcon-centration, pH value,
the population of autotrophic nitrifiers, and clay content in
soils, but negatively correlated with water tension, organic
matter content and cation exchange capacity in soils.
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