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dc.contributor.authorGriffiths, Bryan S
dc.contributor.authorSpilles, Annette
dc.contributor.authorBonkowski, Michael
dc.date.accessioned2012-12-06T14:11:10Z
dc.date.available2012-12-06T14:11:10Z
dc.date.issued2012-06-21
dc.identifier.citationEcological Processes. 2012 Jun 21;1(1):6en_GB
dc.identifier.urihttp://hdl.handle.net/11019/299
dc.identifier.urihttp://dx.doi.org/10.1186/2192-1709-1-6
dc.descriptionpeer-reviewed
dc.description.abstractIntroduction: The availability of essential nutrients, such as nitrogen (N) and phosphorus (P), can feedback on soil carbon (C) and the soil microbial biomass. Natural cycles can be supplemented by agricultural fertiliser addition, and we determined whether the stoichiometry and nutrient limitation of the microbial biomass could be affected by an unbalanced nutrient supply. Methods: Samples were taken from a long-term trial (in effect since 1968) with annual applications of 0, 15 and 30 kg P ha−1 with constant N and potassium. Soil and microbial biomass CNP contents were measured and nutrient limitation assessed by substrate-induced respiration. Linear regression and discriminant analyses were used to identify the variables explaining nutrient limitation. Results: Soil and biomass CNP increased with increasing P fertiliser, and there was a significant, positive, correlation between microbial biomass P and biomass C, apart from at the highest level of P fertilisation when the microbial biomass was over-saturated with P. The molar ratios of C:N:P in the microbial biomass remained constant (homeostatic) despite large changes in the soil nutrient ratios. Microbial growth was generally limited by C and N, except in soil with no added P when C and P were the main limiting nutrients. C, N and P, however, did not explain all the growth limitation on the soils with no added P. Conclusions: Increased soil C and N were probably due to increased net primary production. Our results confirm that C:N:P ratios within the microbial biomass were constrained (i.e. homeostatic) under near optimum soil conditions. Soils with no added P were characterised by strong microbial P limitation and soils under high P by over-saturation of microorganisms with P. Relative changes in biomass C:P can be indicative of nutrient limitation within a site.en_GB
dc.language.isoenen_GB
dc.publisherBiomed Central
dc.relation.ispartofseriesEcological Processes
dc.subjectSoil nutrients
dc.subjectNitrogen
dc.titleC:N:P stoichiometry and nutrient limitation of the soil microbial biomass in a grazed grassland site under experimental P limitation or excessen_GB
dc.typeArticleen_GB
refterms.dateFOA2018-01-12T07:31:32Z


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