Soil organic matter distribution in a floodplain forest

Dr Mark Thomas1, Dr Helen Glanville2, Ms Linda Broekman3, Dr Mark Farrell1

1CSIRO, Glen Osmond, Australia, 2Keele University, Keele, UK, 3Forestry Corporation of NSW, Deniliquin, Australia

Soil organic matter is recognised as being central for healthy soil and broader ecosystem functionality, yet its variability and factors that dive this at the landscape scale are less well understood. This is particularly the case in floodplain forest systems where there is significant local and landscape-scale variation in relation to vegetation type and inundation patters and history, along with underlying geomorphology. Here we report the findings of research carried out in Koondrook-Perricoota State Forest in the NSW Riverina, situated between Barham in the north-west and Moama in the south-east, bordering the River Murray. The forest is very low-lying, with a height gradient of approximately 10 m across its whole length, and thus floodwaters are generally slow-moving following mostly subtle local-scale topographic gradients. We established a series of 10 toposequences throughout the forest capturing local scale variation, and collected soils from the 0-30 cm layer in order to understand how inundation history and seasonality affect multiple soil health indicators, including SOM. Preliminary analyses reveal a 3-4 fold difference in soil organic carbon (SOC) concentration between the highest (3.04%) and lowest (0.89%) concentrations, and a 2-3 fold difference (0.06 – 0.17%) in total nitrogen concentrations, resulting in an average C:N ratio of 11.1 across the 40 sites. These results along with data from ongoing analyses will be discussed.


Biography:

Dr Mark Thomas has >25 years of experience in land resource assessment in Australia and overseas. From a strong foundation in soil science and modern land evaluation Mark innovates to deliver and translates this knowledge to management challenges, principally in the areas of sustainable agriculture and natural resources. As a result of this knowledge transfer there is reduced uncertainty in land-based decision making and increased confidence in public investment and regulation. This has been delivered into some of the most pressing contemporary land issues of the day: northern Australia for new resource regulation and agricultural investment; national bedrock depth mapping to underpin economic objectives and environmental modelling; the gas extraction industries to assess the impacts of extraction activities on communities and primary industries; new sustainable land planning support tools for developing countries, and; new data and methods for wise dryland farming decisions.

Dr Mark Farrell is a Principal Research Scientist and leads the Soil Biogeochemistry Team at CSIRO, based in Adelaide. He has worked in a range of agricultural and natural systems, ranging from the Australian outback to the Arctic and Antarctic. His interests lie in soil organic matter, the microbial community that it harbours, and the ecological functions it delivers, particularly nitrogen supply. Prior to joining CSIRO 9 ½ years ago, he worked at Lancaster and Bangor universities in the UK, where he also attained his PhD.

SOIL ORGANIC MATTER

7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia

Australia

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