Award details

Organic matter in relation to nutrient transformations in grassland soils.

Reference	BBS/E/G/00003018
Principal Investigator / Supervisor	Professor Stephen Jarvis
Co-Investigators / Co-Supervisors	Dr Roland Bol
Institution	Inst of Grassland and Environmental Res
Department	Inst of Grassland and Environmental Res Department
Funding type	Research
Value (£)	130,394
Status	Completed
Type	Institute Project
Start date	01/04/1997
End date	31/03/1999
Duration	24 months

Abstract

The main sources of organic matter in grassland soils are (i) dead roots and leaf material and (ii) animal excreta. The rate at which these materials decompose in soil is strongly influenced by their C:N ratio and also by the chemical nature of the C and N constituents. Decomposition of the various sources of organic matter entails part being mineralised with the release of CO2 and NH4, part being converted into microbial tissue with the immobilisation of N, and part being humified into more resistant forms. Precise chemical characterisation of the C and N in soil organic matter as a whole is rendered difficult by the wide range and complexity of the constituent compounds, but information on the forms of C and N in the various sources of organic matter is valuable in predicting the transformations that occur during the decomposition process. In order to understand and predict the net mineralisation of N in whole soils, some major improvements in understanding of soil organic matter are essential. The partitioning and fate of nitrogen and carbon in plant and animal residues will be examined in field, controlled environment and microcosm studies using stable isotopic signatures of N (both at enriched and natural abundances) and C to define long and short-term turnover and N release. In particular 13C and 15N stable isotopes will be used to provide information on mass balances, fluxes (by measuring signatures in soil generated gases - CO2, CH4, N2O and NOX ) and leachates, and tracers to determine sources and sinks of mobile organic and inorganic C and N compounds in soils. Chemical and physical fractionation and relationships between soil microbial biomass and its community structure and activities will also be examined. The role of macro organic matter will be quantified and interactions between C and N in immobilisation/mineralization and other key N transformations will be determined. The research in this project underpins MAFF funded studies in PU 02, PU 35 and there are current collaborative studies with IACR, Rothamsted, and Royal Holloway College, London.

Summary

unavailable

Committee	Closed Committee - Agri-food (AF)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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