DOI: 10.23637/rex4-ptestyld78623-1
title: Dataset: Exhaustion Land Experiment P test annual crop yields 1986-2023

description: This dataset contains annual crop yield data for the "P Test" plots (plots 1, 3, 5, 7 and 9) of the Exhaustion Land Experiment, 1986-2023, grain and straw uptake of phosphorus (P) and agronomic details. The plots were divided into four sub-plots testing four rates of P fertilizer 1986-1992. Maintenance applications of P were then applied to all plots except the P0 from 2000 onwards. 

The residual effects of fertilizer and manures applied in 1876-1901, and the additional P applied in 1986-1992 have resulted in a wide range of plant available P in the soil. This is the crop data reported by Haefele et al. (2025). Soil Olsen P is published as a separate dataset.
description: The experiment was established in 1856 with four large plots, a fifth was added in 1876 and each was divided to create 10 plots (1-10) in 1876, each receiving a different fertilizer or manure treatment until 1901. No fertilizer or manure was applied 1902-1939. Basal nitrogen (N) fertilizer was applied to all plots 1940-1974; no other fertilizer or manure was applied. No crop was grown in 1975. In 1976 the plots were divided into four sub-plots, and four N fertilizer treatments were applied 1976-1985. 

In 1986 half the plots (1, 3, 5, 7 and 9) received four different P treatments, in the P build-up phase. These plots are known as the "P Test" plots. No P was applied 1993-1999. From 2000 onwards maintenance P fertilizer was applied to all plots, except the Nil (P0). 

**Fertilizer P treatments** (kg P ha<sup>-1</sup> yr<sup>-1</sup>, as triple superphosphate):
 - 1986-1992: the plots were divided into four sub-plots given four rates of P: P0=0, P1=44, P2=87 and P3=131 kg P 
 - 1993-1999: no P applied. Shown as P0 (P0), P0 (P1), P0 (P2), P0 (P3) in the dataset

**Maintenance P** (kg P ha<sup>-1</sup> yr<sup>-1</sup>, as triple superphosphate):
 - 2000-2008: 20 kg P to all plots except to the previous P0 treatment (61.5 kg P applied in error in 2000). Shown as P0 (P0), P (P1), P (P2), P (P3) in the dataset
 - 2009-2015: 15 kg P to all plots except to the previous P0 treatment. Shown as P0 (P0), P (P1), P (P2), P (P3) in the dataset
 - 2016-2023: 15 kg P to all plots except to the previous P1 and P0 treatment . Shown as P0 (P0), P0 (P1), P (P2), P (P3) in the dataset 

Refer to Exhaustion Land Experiment plans and fertilizer treatments, Phase IV and V for more details (see Related Documents).
description: **Grain and straw yields**:
Grain and straw subsamples were taken at harvest from each sub-plot, oven-dried and ground &lt; 0.5 mm. Yields are reported at 85% dry matter. The straw yields do not include stubble. 

**Crop P content**:
- **Total P** was determined until 1996 after dry ashing (Piper, 1942), on a Spekker Technicon Auto Analyser, or using Alpkem Flow Injection Analysis, using the method of Fogg & Wilkinson (1958). From 1996 onwards total P was determined by open tube nitric perchloric digestion (Zarcinas et al., 1987), and analysis by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry, Optima 7300DV ICP-OES, Perkin Elmer, CT, USA). 
- **P uptake** in grain and straw is calculated from the yield at 100% dry matter and %P in the grain and straw. 

**References**:
- Fogg, D.N. and Wilkinson, N.T. (1958). The colorimetric determination of phosphorus. Analyst, London, 83:406-414.
- Piper, C.S. (1942) Soil and plant analysis. The University of Adelaide, Adelaide, Australia.
- Zarcinas, B.A., Cartwright, B., Spouncer, L.R., 1987. Nitric acid digestion and multi-element analysis of plant material by inductively coupled plasma spectrometry. Communications in Soil Science and Plant Analysis 18, 131-146.
description: Individual plot yields were taken from Rothamsted Research archives. Agronomic information (sowing dates, variety, etc) taken from Rothamsted Experimental Station Annual Reports. The P content is derived from analysis made by the Analytical Chemistry Unit, Rothamsted Research, Harpenden. 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. 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.