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You are free to re-use this data but YOU MUST CITE AS: Rothamsted Research (2018), Broadbalk soil total nitrogen content. Electronic Rothamsted Archive https://doi.org/10.23637/bk-oadata-soiln-01.
Click the chart above for a PDF version.
Data used for this chart are available to download as an Excel Spreadsheet: Broadbalk Soil total N data.xlsx .
Supporting information is also available: Broadbalk Soil total N treatment details.xlsx .
Publication date V1. 2018/12/17
Last updated V1. 2018/12/17
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The figure shows the measured 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 N concentration has remained almost constant in the unfertilized plot (nil), and the plot given PK since the start of the experiment. Inorganic fertilizer with nitrogen (N3PK) has enhanced soil N a little, probably due to increased returns of organic matter in crop roots, chaff and stubble. There has been a slight decline in soil N on these plots in the last 20 years. The treatment given FYM (35 t ha-1) since 1843 now has about three times the concentration of soil total N as the unfertilized plot. Increases due to FYM were greatest in the initial years of the experiment. The same trends can be seen in the FYM treatments that started in 1885 and 1968. The decline in soil N on the FYM plots in the 1920s and 1930s was because FYM was not applied in the the years when the plots were fallowed to control weeds. The decline since 2000 on Plot 1 (FYM+N, 1968-2000) is because FYM has not been applied since 2000.
CROPPING AND TREATMENTS
Continuous wheat: Wheat grown every year since autumn 1843, except when parts of the experiment were fallowed to control weeds. The experiment was divided into 10 sections in 1968; data shown are mean of sections 1, 6 and 9, which are those sections in continuous wheat (except for occasional fallow). Plot 1 data is from section 6 only (there is no plot 1 on sections 1 and 9). In other sections, not included in this chart, wheat is grown in rotation with other crops.
Nil: Plot 3 - No fertilizer or manure applied since 1852.
PK: Plot 5- PKMg applied since 1852 (P withheld since 2001).
N3PK: Plot 8 - PKMg + 144 kgN ha -1 applied since 1852 (P withheld since 2001).
FYM since 1843: Plot 2.2 - 35 t ha -1 of farmyard manure applied since 1843.
FYM since 1885 + N since 1968: Plot 2.1 - 35 t ha -1 of farmyard manure since 1885 plus 96 kgN ha -1 since 1968, plus 144 kgN ha -1 since 2005.
FYM+N 1968-2000; N4 since 2001: Plot 1 - 35 t ha -1 of farmyard manure 1968-2000 only, plus PK + 96 kgN ha -1 1968 -1984, plus PK + 192 kgN ha -1 1985-2000, 192 kgN only since 2001.
Fallowing: Between 1926 and 1967 the experiment was divided into five sections which were bare fallowed sequentially one year in five to control weeds. Wheat was grown in the other four years.
Liming: Lime (calcium carbonate, often referred to as chalk) has been applied since the 1950s to maintain soil pH at a level which does not limit yield.
Herbicides: Herbicides were introduced in 1964; previously weeds were controlled by hand-hoeing or by fallowing and cultivation.
Modern cultivars: Modern short-strawed, high-yielding cultivars since 1968.
Fungicides: spring and summer fungicides as necessary since 1978
Margaret Glendining, Andy Macdonald, Paul Poulton, Sarah Perryman.
The data contained in this spreadsheet are derived from measurements made at Rothamsted Research, Harpenden. The data presented is mean data from selected plots and sections only. Most of the chemical analysis was carried out by the Rothamsted Research Analytical Unit, which uses standards and check samples to ensure quality control. 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, 1997, 2000, 2005 and 2010 are by combustion (LECO). The complete data set, including the raw data used to derive the mean values, is available from the e-RA Curators.
For further information about the experiment see Broadbalk Winter Wheat Experiment and the key references below. For further information about the fertilizer treatments see Broadbalk Fertilizer Treatments (pdf). For further information about the soil, including site details and soil weights, see Broadbalk Soils. See also the Rothamsted Guide to the Classical Experiments (2018), pp 7-18.
The Broadbalk experiment has also been used to investigate the fate of 15N-labelled fertilizer applied to winter wheat in spring and autumn (Powlson et al, 1986; Shen et al, 1989), the long-term effects of inorganic nitrogen fertilizer on soil nitrogen (Glendining et al, 1996), nitrate leaching (Goulding et al, 2000), the turnover of organic carbon and nitrogen in the soil (Jenkinson, 1990) and to develop models of the turnover of nitrogen in crop and soil (Jenkinson & Parry, 1989; Bradbury et al, 1993). See Key References below for more details.
Please contact the e-RA Curators for further information, and assistance with questions about the data or its interpretation:
Department of Computational and Analytical Sciences (CAS)
Rothamsted Research, Harpenden, Herts, AL5 2JQ
The Long-term Experiments and weather stations are supported by the Lawes Agricultural Trust and BBSRC National Capability Funding (BBS/E/C/000J0300) recognising the national and international importance of the data.