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dc.contributorWhitbread, Anthonyen_US
dc.contributorBlair, Nellyen_US
dc.contributorBlair, Graemeen_US
dc.creatorManu, V.en_US
dc.identifier.citationV. 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.en_US
dc.description.abstractMaintenance 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 (<125 lm) fractionen_US
dc.sourceSoil Use and Management;30,(2014) Pagination 517,523en_US
dc.titleCarbon status and structural stability of soils from differing land use systems in the Kingdom of Tongaen_US
dc.typeJournal Articleen_US
cg.creator.idWhitbread, Anthony: 0000-0003-4840-7670en_US
cg.subject.agrovocsoil organic matteren_US
cg.subject.agrovocpacific islandsen_US
cg.subject.agrovocsoil aggregatesen_US
cg.contributor.centerMinistry of Agriculture, Food , Forestry & Fisheries Departmenten_US
cg.contributor.centerInternational Crops Research Institute for the Semi-Arid Tropics - ICRISATen_US
cg.contributor.centerOurfing Partnershipen_US
cg.contributor.centerUniversity of New England - UNEen_US
cg.contributor.crpCGIAR Research Program on Dryland Systems - DSen_US
cg.contributor.funderNot Applicableen_US
dc.identifier.statusLimited accessen_US

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