DOI: 10.23637/wsc10-wltlcation-01
title: Dataset: Woburn long-term liming experiment exchangeable cations re-analysed

description: The experiment tests the effects of different amounts of lime (and thus soil pH), P and K on a sequence of arable crops, on a sandy soil at Woburn Experimental Farm, from 1962-1996. Archived topsoil samples from six years between 1964 and 1989 were re-analysed in 2019 for a range of soil exchangeable cations, by extraction with ammonium nitrate (NH<sub>4</sub>NO<sub>3</sub>). Topsoil was analysed from all plots and sub-plots (where present), except sub-plots given Mg in 1974-1978. 


There is a parallel experiment at Rothamsted Experimental Farm. This experiment was discontinued in 1997.
description: Period 1 (1962-1980): four lime levels with and without fertilizer P and K. Period 2 (1981-1996): four lime levels with four P levels. 2 replicates (blocks). 
 - Topsoil (0-18 or 0-23cm) sampled in 1964, 1967, 1974, 1979, 1983 and 1989
 - Sub-plots given Mg in 1974-1978 were not included (the 1974 and 1979 samples)
 - From 1981 basal fertilizer K and Mg was applied to all plots
 - 12-20 soil cores taken from the central area of each plot and combined to make one sample
 - Soil samples taken in autumn, after harvest and before ploughing for the next crop
 - Archived air-dried sieved (&lt;2mm) soils re-analysed in 2019
 - Exchangeable cations Al, Ca, Cu, Fe, K, Mg, Mn, Na and Zn, mg/kg dry soil
 - Measured by extraction with 1 M ammonium nitrate (NH<sub>4</sub>NO<sub>3</sub>)
 - Cations detected by ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometer)
 - Negative values shown as zero.
description: *Note* the included Excel file: _*01-WLTLCATION.xlsx*_ contains the same data as the CSV files below. The Excel file contains each of the CSV files as an Excel worksheet and is provided for users who prefer Excel over CSV.
### Contents

|File|Dataset Name|Description|
|----|------------|-----------|
|soil_data.csv|Soil data|The main data table containing soil exchangeable cation data for archived soil sampled in 1964, 1967, 1974, 1979, 1983 and 1989, re-analysed in 2019. Topsoil was analysed from all plots and sub-plots (where present), except sub-plots given Mg in 1974-1978. Exchangeable cation extraction by ammonium-nitrate method. Cations were detected by ICP-OES. Any negative values were converted to zero. |
|liming_factor_data.csv|Liming treatment factor level descriptions|Describes the different liming treatment factor levels used, 1962-1996.|
|p_factor_data.csv|P treatment factor level descriptions|Describes the different P treatment factor levels used, 1962-1996. |
|k_factor_data.csv|K treatment factor level descriptions|Describes the different K treatment factor levels used, 1962-1980. From 1981 basal K was applied to all plots.|
|detection_limit_data.csv|Detection limit data|Describes the limits of detection of the ICP-OES for each cation.|
|notes_data.csv|Notes|Additional explanatory notes for records in the soil_data table|
description: **Detection limits (DL) of the ICP-OES.** 
These values provide an indication of the lower values for detection by the ICP-OES. DL (mg/kg dry soil) is calculated as 3x standard deviation of blanks. 

|           |     Al       |     Ca     |     Cu     |     Fe     |     K     |     Mg     |     Mn     |     Na     |     Zn     |
|--|:--:|:--:|:--:|:--:|:--:|:--:|:--:|:--:|:--:|
|DL | 0.33 | 1.43 | 0.02 | 0.23 | 3.18 | 0.21 | 0.06 | 0.76 | 0.02 | 

**Basal Fertilizer** See Lime and Fertilizer Treatments
 - Fertilizer N applied to all plots from 1964
 - Fertilizer K applied to all plots from 1981
 - Fertilizer Mg applied to all plots from 1981
description: The original archived soil samples were stored in the Rothamsted Sample Archive. The chemical analysis was carried out in the Analytical Unit of Rothamsted Research in 2019. 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.