Spatial and temporal variability in organic carbon observed in soil under lucerne pastures

Richard Hayes, Mark Conyers, Graeme Poile, Albert Oates, Guangdi Li

Research output: Book chapter/Published conference paperConference paperpeer-review

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Two field trials established in 2005 were sampled during 2008-09 to observe temporal and spatial variability in soil organic carbon levels under mature lucerne (Medicago sativa) stands. The study was conducted at Binalong and Gerogery in the high-rainfall cropping zone of southern New South Wales, Australia. Four replicate plots were selected at each location and sampled monthly between February 2008 ' January 2009 by taking 10 soil cores at 0-0.1m depth and analysing the samples using the Walkley'Black and Heanes methodologies. Plot area was no more than 10 m2, and the 4 plots sampled at each location were no more than 20 m apart. Temporal variation in organic carbon levels during the 12 month sampling period was 24-76% (mean 37%) and spatial variation was observed to be 13-46% (mean 30%) using the standard Walkley'Black test with samples sieved to <2 mm. Analysing samples using the Heanes method reduced the mean temporal variability from 37% to 29% and mean spatial variability from 30% to 28%. A subset of samples were ground to a fine powder to increase the homogeneity of the sample before being reanalysed, but temporal and spatial variation in organic carbon values were still shown to be 29% and 24%, respectively. This study demonstrates the magnitude of sampling variability likely to be encountered when quantifying soil organic carbon for possible inclusion in future carbon-emissions trading schemes. Aspects requiring further research are discussed.
Original languageEnglish
Title of host publication15th AAC
Subtitle of host publicationFood security from sustainable agriculture
EditorsH. Dove, R. Culvenor
Place of PublicationAustralia
PublisherThe Regional Institute
Number of pages4
Publication statusPublished - 2010
Event15th Australian Agronomy Conference - Lincoln, New Zealand, New Zealand
Duration: 15 Nov 201018 Nov 2010


Conference15th Australian Agronomy Conference
Country/TerritoryNew Zealand


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