DOI: 10.23637/wxw6-soil7632-01
title: Dataset: Woburn Continuous Wheat Experiment soil data 1876-1932

description: This dataset contains the soil pH, percentage of total soil carbon (C) nitrogen (N) phosphorus (P) and exchangeable calcium (Ca) in the topsoil (0-23cm) of the Woburn Continuous Wheat experiment, 1876 to 1932. Baseline measurements were taken in November 1876 before the start of the experiment. The soil was then sampled from each plot in 1888, 1927 and 1932. Selected plots were also sampled in 1898 and 1919. The dataset also contains details of the fertilizer, manure and lime treatments applied 1876-1926. No fertilizer, manure or lime was applied after 1926. 
The soil at Woburn contained little free calcium carbonate, and soil pH was 6.1 in 1876. Consequently, where ammonium sulphate was applied (plots 2, 5 and 8) the soil soon became acidic and yields declined markedly within 20 years. These were the first experiments in the UK where lime was applied to try to correct soil acidity.

Data from Crowther (1936) and Mattingly et al (1975), see Resource Provenance.
description: The Woburn Continuous Wheat experiment originally had 11 plots (1-11), with different fertilizer and manure treatments. Some plots were divided into sub-plots (a and b) from 1882, and into sub sub-plots (i and ii) from 1905, to test different treatments, mainly with and without lime. Full details are given in Related Documents.
- **Soil pH** measured in water by quinhydrone electrode. Analysed in 1932 (earlier samples re-analysed).
- **Soil C** total soil carbon, measured by the Bangor method. There is very little free calcium carbonate, so this is equivalent to soil organic carbon. 
- **Soil N** total soil nitrogen, measured by the Kjeldahl method.
- **Exch Ca** exchangeable calcium extracted with 0.5M acetic acid. Analysed in 1932. 
- **Total P** total soil P by Technicon AutoAnalyser after fusion with sodium carbonate, method of Salt (1968). 
- **Org P_ignition** Organic P by ignition, method of Saunders and Williams (1955). 
- **Org P_extraction** Organic P by extraction with HCl then NaOH, method of Mehta et al (1955).
description: Data expressed on air-dried soil basis. Ground soil, passed through a 0.5mm sieve. Soil samples in 1876, 1888 and 1898 taken with sample box 15cm x 15cm x 23cm deep, composite of three holes. 1927 sample cut by spade 23cm deep, 4-5 holes per plot combined into composite samples. 1932 sample taken with a small semi-cylindrical sampler, 20 holes per plot, soil combined into composite samples.
description: - Soil C, N, pH and Ca data from Crowther, E. M. (1936) "Chapter XXII. The soils of the Woburn plots. ", Fifty years of the field experiments at the Woburn Experimental Station. Rothamsted Monographs on Agricultural Science. (Russell E.J. and Voelcker J.A. (eds) - Longmans, Green and Co,), No. 7., 315-345. 
- Total and organic P data from Mattingly et al, 1975, main plots only. In accordance with the Joint Code of Practice for Research at Rothamsted, data processing in e-RA follow rigorous standard operating procedures to ensure the quality and correctness of data collected in the field through to depositing in the e-RA database. To ensure quality control during data inputting, the data sets were typed on two separate occasions (double data entry). During the second typing (verification) the data values were compared with those typed on the earlier occasion, and any discrepancies were resolved before verification continued. This procedure also set out how to handle situations where the written records were illegible or ambiguous. This procedure avoided visual checking of data, which can be very inaccurate. The soil was relatively fertile at the start of the experiment, thought to be due to large FYM applications to the preceding arable rotation. Soil fertility generally declined, except in plots given FYM. 
The high C:N ratio of some wheat plots (eg Plot 7 and 8a) was due to the presence of coal and charcoal in the soil (Crowther, 1936, p 319). 

**Methods of Analysis references:**
- Mehta, N.C., Legg, J.O., Goring, C.A.I. and Black, C.A. (1954). Determination of organic phosphorus in soils. I. Extraction method. Soil Science Society of America, Proceedings 18, 443-449 
- Salt, P.D. (1968) The automatic determination of phosphorus in extracts of soils made with 0.5M sodium hydrogen carbonate and 0.01M calcium chloride. Chemistry and Industry, 584-586. 
- Saunders, W.M.H. and Williams, E.G. (1955). Observations on the determination of total organic phosphorus in soils. Journal of Soil Science, 6: 254-267.