Soil biological indicators: Organic Farming Systems. Dr. Rachel Creamer, Prof. Bryan Griffiths Johnstown Castle Environment Research Centre. Acknowledgements: A Bispo – ADEME, Karl Ritz – Cranfield University, Scottish Agricultural College, SCRI, Dundee.
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Dr. Rachel Creamer, Prof. Bryan Griffiths
Johnstown Castle Environment Research Centre
Acknowledgements: A Bispo – ADEME, Karl Ritz – Cranfield University,
Scottish Agricultural College, SCRI, Dundee
Responsible for many key ecosystem functions
Turnover 50,000 kg fresh material ha-1 yr-1
Predicted 20 MT CO2-C yr-1 sequestered (NL)
Soil fauna represent 10% of biomass but are responsible for 30% of N mineralisation
Cycling of energy and nutrients intimately associated with the soil food webWhy soil biology as indicators?
Soil chemistry – NO3-, NH4+, DOC, DON, pH, soil C:N
Soil function – Potential nitrification and denitrification rates in lab assay. - Monthly in situ gas fluxes, CO2, N2O
Microbiology – Nucleic acid analysis of: nitrifiers, denitrifiers, methanotrophs, eubacteria and fungi. - ELFA, ester-linked fatty acids.
Soil animals – counted and identified where possible to species.
Earthworms, Microarthropods, Nematodes, ProtozoaComprehensive set of field measurements
Samples taken in 2006 (summer, autumn) and 2007 (spring, summer, autumn). Analytical completion planned for end March 2008
biodiversity and recovery of losses
decomposition / physical strength/
chemistry / biodiversity
BUT increased losses of leachates and gases
The field under organic management showed significantly better soil nutritional and microbiological conditions; with increased level of total nitrogen, nitrate and available phosphorus, and an increased microbial biomass content, and enzymatic activities (acid phosphatase, protease and dehydrogenase). No consistent increase in total organic carbon was observed.
Birkhofer et al., 2008 (Soil Biology and Biochemistry)
Long-term organic farming and the application of farmyard manure promoted microbial biomass and fostered natural enemies and ecosystem engineers. Application of farmyard manure increased the activity and biomass of decomposer biota. Mineral fertilizers and herbicide application, reduced natural pest control. The combined application of mineral and organic fertilizers appeared to counteract beneficial effects of organic fertilizers, such as enhanced microbial biomass or reduced pest abundance. However 23% higher yields in systems receiving min fertilisers and herbicides
Fließbach et al., 2006 (Agriculture, Ecosystems and Environment)
Both organic C and biological soil quality indicators were clearly dependent on the quantity and quality of the applied manure types, but soil microbial biomass and activities were much more affected than organic C.Literature overview