DOI: 10.23637/rpg5-transects-01
title: Dataset: Park Grass 1993 soil transects across adjacent pairs of sub-plots with contrasting treatments

description: Soil transects were taken in August 1993 across the boundaries between four pairs of adjacent unlimed 'd' sub-plots with different fertiliser treatments on the Park Grass experiment, to assess the extent to which fertiliser in one plot affects the soil of the adjacent plot. All the soils were analysed for pH (in water); the soil from two pairs of plots were also analysed for Olsen P and exchangeable cations. 
The data shows that there has been some mixing across the plot boundaries, possibly because, over 137 years (when the samples were taken) some fertiliser may not have been applied right up to the plot boundary or might have been spread over the boundary. It also seems likely that plant roots would have spread into adjacent plots looking for nutrients; the roots subsequently die leaving slightly enriched residues in the soil. However, in all cases, soil from &gt; 50 cm away from the boundary is less variable. This is the data discussed in Poulton et al, 2026 (in preparation).
description: Two transects (50 and 100 cm from the plot edge) were taken across the boundaries between four pairs of adjacent plots (14-2d and 1d, 1d and 2d, 4-1d and 4-2d, 11-2d and 12d) which had very contrasting fertiliser treatments, on 13th August 1993. Soil cores (0-23 cm depth) were taken at 0, 10, 20, 30, 40, 50, 65, 80, 100, 125, 150, 175, 200, 250, 300, 350, 400, 450 and 500 cm from the shared plot boundary, a total of 19 samples from each transect from each plot. The common boundary between each plot pair is indicated by distance zero and sample 1. All pairs of plots share the same sample for distance zero, except pairs 1d and 2d, where the transects were not contiguous (see figure). In the dataset negative distances from the boundary indicate samples taken on the east side of the common boundary, positive distances indicate samples taken on the west side of the common boundary, to aid plotting the data.
description: An Excel file, rpg5_transects_01.xlsx, contains Park Grass transect data for 1993. Frictionless CSV files are also provided.
description: **Soil properties**:

Soil cores from the same point on each of the duplicate transects were bulked, dried and ground &lt; 2 mm and analysed.

**Soil pH** in boiled, deionised water

**Soil Olsen P**, a measure of plant-available soil P. Measured after extraction with 0.5<i>M</i> NaHCO<sub>3</sub> (Olsen, 1954) using a modified method of Murphy and Riley (1962) on a continuous segmented colourimetric flow analyser (Skalar SANPLUS, Skalar Analytical BV, Breda, Netherlands). 

**Soil exchangeable cations**: 
potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), aluminium (Al) and iron (Fe) leached with 1<i>M</i> ammonium acetate (Metson, 1956) and determined by ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometry), (Agilent 5900 SVDV ICP-OES, Agilent Technologies 5301 Stevens Creek Blvd. Santa Clara, CA 95051, USA).
description: This dataset is from measurements made by Paul Poulton, and analysed by the Analytical Chemistry Unit, Rothamsted Research, Harpenden. 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. **References for methods of analysis**:

- **Metson, A.J. (1956)**. Methods of chemical analysis for soil survey samples. New Zealand Soil Bureau, Bulletin 12.
- **Murphy, J. and Riley, J.P. (1962)** A Modified Single Solution Method for the Determination of Phosphate in Natural Waters. Analytica Chimica Acta, 27, 31-36 
- **Olsen, SR, Cole, CV, Watanabe, FS and Dean, LA (1954)** Estimation of Available Phosphorus in Soils by Extraction with Sodium Bicarbonate. USDA Circular No. 939, US Government Printing Office, Washington DC