Broadbalk: Changes in soil organic carSbon t/ha (0-23cm ) figure
Long-term changes in soil organic carbon content (t/ha) in selected treatments of the Broadbalk experiment, where winter wheat has been grown every year since autumn 1843. SOC in t/ha, calculated from %SOC and soil weights, adjusted for changes in soil bulk density in FYM treatments.
Soil organic carbon has been measured at intervals since 1865. Data is mean of sections 1, 6 and 9, continuous winter wheat (except for occasional fallow), from six selected plots (3, 5, 8, 2.1, 2.2 and 1). The starting values in 1843 and the later FYM treatments have been estimated. The sections were regularly fallowed from 1926 to 1967, FYM was not applied in fallow years (shown as dashes in the figure). Lime (chalk) has been applied since the 1950s to maintain soil pH at a level which does not limit yield. Herbicides were introduced in 1964; previously weeds were controlled by cultivation or fallowing. Modern high-yielding cultivars have been used since 1968. Spring and summer fungicides have been applied as necessary since 1978.
Soil samples taken in 1881, 1893, 1914, 1936 and 1944 were re-analysed in 2001-4 for total C by combustion (LECO) and CaCO3-C by manometry. SOC is calculated as Total C minus CaCO3-C. Data in 1865 are derived from the original Soda Lime analyses (for Total N) and C:N ratios for 1893 (for organic C). Data for 1966 are corrected Walkey-Black values for organic C. Data for 1987 are Tinsley for organic C. Data for 1992 onwards are Total C by combustion (LECO) minus CaCO3-C by manometry.
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YOU MUST CITE AS: Rothamsted Research (2014). Broadbalk soil organic carbon content 1843-2010 Electronic Rothamsted Archive, Rothamsted Research 10.23637/KeyRefOABKsoc
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Soil organic carbon, t/ha in topsoil (0-23cm from the following plots):
This dataset is derived from measurements made by the Analytical Chemistry Unit, Rothamsted Research, Harpenden. The data presented is mean data from selected plots and sections only. The complete data set, including the raw data used to derive the mean values, is available from the e-RA curators.
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