Soil organic carbon sequestration and turnover in leucaena-grass pastures of southern Queensland

Conrad, Kathryn A., Dalal, Ram C., Dalzell, Scott and Menzies, Neal W. (2012). Soil organic carbon sequestration and turnover in leucaena-grass pastures of southern Queensland. In: Lucy Burkitt and Leigh Sparrow, Proceedings of the 5th Joint Australian and New Zealand Soil Science Conference 2012. Soil Science: Joint Australian and New Zealand Soil Science Conference: Soil solutions for diverse landscapes, Hobart, Australia, (251-254). 2 - 7 December 2012.

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Name Description MIMEType Size Downloads
Author Conrad, Kathryn A.
Dalal, Ram C.
Dalzell, Scott
Menzies, Neal W.
Title of paper Soil organic carbon sequestration and turnover in leucaena-grass pastures of southern Queensland
Conference name Soil Science: Joint Australian and New Zealand Soil Science Conference: Soil solutions for diverse landscapes
Conference location Hobart, Australia
Conference dates 2 - 7 December 2012
Proceedings title Proceedings of the 5th Joint Australian and New Zealand Soil Science Conference 2012
Place of Publication Victoria, Australia
Publisher Australian Society of Soil Science
Publication Year 2012
Sub-type Fully published paper
ISBN 9780646591421
Editor Lucy Burkitt
Leigh Sparrow
Start page 251
End page 254
Total pages 4
Collection year 2013
Language eng
Formatted Abstract/Summary
The sequestration of soil organic carbon (SOC) in agricultural systems has the potential to partially mitigate climate change by removing carbon dioxide (CO2) from the atmosphere. Furthermore, incorporating a forage legume into grazing systems may aid C storage, as typically mature pasture soils are nitrogen (N) limited. In Queensland, Leucaena leucocephala, a leguminous shrub, is known to improve the N fertility of grazing lands. Despite this, there is limited research on the C and N dynamics beneath leucaena-grass pastures. This study assessed the potential of leucaena to sequester SOC by estimating the origin (C3 or C4), quantity (t/ha) and vertical distribution (m) of C stocks, in bulk fractions. A chronosequence of leucaena stands was sampled to a depth of 1 m and then analysed for C, N and stable C isotopes (δ13C). Pasture type affected C stocks within the upper 0.3 m (grass pasture < leucaena mid-row = leucaena row). On average, stocks were 14 % higher beneath leucaena rows compared to pure pasture-grass swards. Stand age also affected C stocks in the 0.3 m zone, with a 16 – 23 % increase in SOC over 40 years. However, this trend was not evident below 0.3 m suggesting other factors were affecting SOC storage at lower depths. Cumulative C3-C stocks were also significantly higher beneath leucaena stands. However, irrespective of pasture type, the majority of C displayed a C4 signature. This suggests that direct C3-C contributions to SOC from leucaena were small (25%) compared to the effect of improving N fertility and hence C4 grass productivity in N-limited, mature pasture soils.
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Document type: Conference Paper
Collections: School of Agriculture and Food Sciences
Official 2013 Collection
 
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Created: Fri, 21 Dec 2012, 12:18:41 EST by Ms Ramona Hooyer on behalf of School of Agriculture and Food Sciences