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Carbon status and structural stability of soils from differing land use systems in the Kingdom of Tonga

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Title Carbon status and structural stability of soils from differing land use systems in the Kingdom of Tonga
 
Creator Manu, V.
 
Contributor Whitbread, Anthony
Blair, Nelly
Blair, Graeme
 
Description Maintenance of soil carbon stocks is vital for the environment at large and for maintenance of soil
chemical, physical and biological fertility. Tonga represents a country in agricultural transition from
subsistence to commercial production and whilst this is good for the national economy the impact on
soil resources is less clear. The major cropped soils, fallow vegetation types and forest systems of
Tonga were identified in each island group and samples of representative soils (0.15 m depth) from
each land use unit were taken. Total carbon (CT) and d13C were measured and labile carbon (CL)
determined by oxidation with 333 mM KMnO4. These data were used to determine the carbon
management index (CMI) and the proportion of carbon from C4 species in the CT pool. Relative to
primary forest, the soil CT and CL generally declined with changes in vegetation and more intense
mechanical tillage. The contribution of C4 plants to soil C increased with intensity of mechanical
tillage and the prevalence of C4 guinea grass (Panicum maximum Jacquin) fallow. The changes in soil
C were reflected in the CMI, and CL was a more sensitive indicator of change than CT. These data
indicates that all land use systems have experienced a large net loss of soil C relative to the forest
systems. Soil mean weight diameter (MWD) decreased significantly with increased intensity of
mechanical tillage and to a lesser extent with the intensity and length of cropping. The relationship
between soil MWD and soil C was similar with soil CT and CL. Grass fallow was as effective as
permanent vegetation systems in improving soil MWD and lowering the micro-aggregate (
 
Date 2017-01-05T19:44:22Z
2017-01-05T19:44:22Z
 
Type Journal Article
 
Identifier http://oar.icrisat.org/id/eprint/9459
https://mel.cgiar.org/reporting/download/hash/K1vWVkfQ
V. Manu, Anthony Whitbread, Nelly Blair, Graeme Blair. (30/6/2014). Carbon status and structural stability of soils from differing land use systems in the Kingdom of Tonga. Soil Use and Management, 30 (4), pp. 517-523.
https://hdl.handle.net/20.500.11766/5351
Limited access
 
Language en
 
Rights CC-BY-NC-4.0
 
Format PDF
 
Publisher Wiley
 
Source Soil Use and Management;30,(2014) Pagination 517-523