『Abstract
Soluble organic nitrogen (SON) plays a vital role in ecosystem
N cycling processes and is controlled by a number of biotic and
abiotic factors. We compared soil SON availability, microbial
biomass, protease and asparaginase activities and phospholipids
fatty acid (PLFA) profiles at the 0-15 and 15-30 cm layers in
10 year old tea plantations of two genotypes - Oolong tea (Camellia
sinensis (L.) O. Kuntze cv. Huangjingui) (designated as ‘OT’)
and Green tea (C. sinensis (L.) O. Kuntze cv. Fuyun 6)
(designated as ‘GT’) - established at different slope positions.
Concentrations of soil SON measured by the 2 M KCl extraction
under the OT plantation were greater than under the GT plantation,
while concentrations of soil SON were greater in the middle slope
(MS) and lower slope (LS) positions than in the upper slope (US)
position. Trends in soil microbial biomass C and N and protease
and asparaginase activities between the two genotypes and across
the slope positions were similar to the SON pools. The fungal-to-bacterial
ratios were higher in the US position than in the MS and LS positions
and higher under the GT plantation than under the OT plantation.
Results from this study support that the genotype and the slope
position are key factors controlling the availability of soil
SON in tea plantations and also imply the importance of plant
traits (e.g. litter quantity and chemistry) and soil texture in
determining overall soil N availability and transformation processes
and microbial community composition at the landscape level.
Keywords: Soil soluble organic nitrogen (SON); Camellia sinensis
(L.) O. Kuntze; Genotype; Slope position; Phospholipid fatty acid
(PLFA); Protease』
Introduction
Materials and methods
Site description and sample collection
Analysis of soil properties and solid state 13C NMR
spectroscopy of leaf litter and roots
Analysis of soil soluble organic N and C
Analysis of soil microbial biomass and enzyme activities
Analysis of phospholipid fatty acid and microbial community composition
in soil
Statistical analysis
Results
Properties of soil and leaf litters and roots in tea plantations
of different genotypes at different slope positions
Soil SON concentrations under tea plantations of different genotypes
at different slope positions
Soil microbial biomass and enzyme activities under tea plantations
of different genotypes at different slope positions
Soil PLFA profile and microbial community composition under tea
plantations of different genotypes at different slope positions
Discussion
Effects of tea genotype on soil SON
Effects of slope position on soil SON
Conclusions
Acknowledgements
References