Long-term changes in soil nitrogen concentration figure
Long-term changes in total % nitrogen concentration in the topsoil (0-23 cm) in selected treatments of the Broadbalk experiment, where winter wheat has been grown most years since 1843 (continuous wheat).
Soil total N % 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 N by combustion (LECO). Data in 1865 are the original Soda Lime analyses from Dyer (1902), corrected to be equivalent to LECO. Data for 1966 and 1987 are by Kjeldahl analysis for Total N. Data for 1992 onwards are Total N by combustion (LECO).
This dataset is available under a Creative Commons Attribution Licence (4.0).
YOU MUST CITE AS: Rothamsted Research (2018). Dataset: Broadbalk Soil Total % Nitrogen Content, 1843-2010 Electronic Rothamsted Archive, Rothamsted Research https://doi.org/10.23637/BK-oadata-soilN-01
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Soil %N 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.
The Analytical Chemistry Unit follows the Joint Code of Practice (JCoPR) and participates in European Quality Assurance programmes. All performance is strictly monitored using certified external standards alongside in-house standard materials. Standards and check samples are monitored and recorded.
Broadbalk has also been used to investigate the fate of 15N-labelled fertilizer applied to wheat (Powlson et al, 1986; Shen et al, 1989), the long-term effects of N fertilizer on soil N (Glendining et al, 1996), nitrate leaching (Goulding et al 2000) and the turnover of C and N in the soil (Jenkinson, 1990), see Key References.
For further information and assistance, please contact the e-RA curators, Sarah Perryman and Margaret Glendining using the e-RA email address: firstname.lastname@example.org