Ureolytic nitrification activities in forest and tea (Camellia sinensis) plantation soils and evaluation of ureolytic nitrifier sensitivity to pestiCides

Abstract

An experiment was conducted in 1992 to Compare ureolytic nitrification activities in soil uner tea (Camellia
sinensis (L) 0 Kuntze) cu1tivation and forest land adjacent to the tea plantations .Recovery of nitrate from the sOil
samples oftea plantations following incubation with urea confirmed that the actlve nitrificatiOn occurred even in the pH
range of 4.5-5.5. A slight increase in ureolytic nitrification activity in sections showing higher yield ofmade tea was
detectable in plantations using lower dosages of synthetic fertilisers. Such a relationship was not detected m samples
from plantations using a higher dose of chemical fertilisers. Likewise neither the age, nor the organic carbon (%) and PH
were related to the differences in ureolytic- nitrification activity observed in the samples. Comparison of the ureolysis
and nitrification rates between plantation samples and the corresponding forest samples showed that this actiVIty was
lower in tea plantations in all cases. The ureolytic nitrifier strains isolated from tea plantatlOns were able to grow m
culture plates incorporated with several structurally different types of pesticides.