DOI: 10.23637/rbk1-yld6822-01
title: Dataset: Broadbalk Wheat annual grain and straw yields 1968-2022

description: Annual winter wheat grain and straw yields for each treatment plot of the Broadbalk Wheat Experiment, 1968-2022, with details of all fertilizer and manure applications. Also other agronomic information, including sowing and harvest dates, and winter wheat cultivars.
description: The Broadbalk Wheat Experiment was started in autumn 1843 to investigate the effects of fertilizers containing N, P, K, Na and Mg in various combinations, and organic manure, on the yield of winter wheat grown continuously. The treatment STRIPS (3-22) extend the whole length of the field; each strip tests a different fertilizer or manure treatment. In 1926 the strips were divided into five SECTIONS (I-V), bare fallowed in sequence to control weeds. There were further divisions in 1955 making seven Sections (IA-VB). Each PLOT is a unique strip\section combination. In 1968 the experiment was divided into ten Sections (0-9), to allow the comparison of wheat grown continuously with wheat in a three or five-year rotation. Strip 1 was added in 1968, on Sections 2-7 only. 
Sections 0, 1, 8 and 9 remained in continuous winter wheat. In Sections 2-7 wheat was grown in rotation with other arable crops (potatoes, beans, oats or forage maize) and fallow. In 1979 Section 6 reverted to continuous wheat. Section 0 has had straw incorporated each year since 1986; straw is removed from all other sections. Section 8 has never received herbicides; it is bare fallowed every 5-8 years to control weeds. Section 6 has had restricted pesticide use since 1985 (no spring or summer fungicides). Yields from non-wheat crops are published separately. See section_names.pdf for full details of layout and the cropping plans for details of the different crop rotations.
description: An Excel file, 01-BKyld6822.xlsx, contains the Broadbalk wheat grain and straw yields, fertilizer and manure treatment details and cropping information, for 1968-2022. Frictionless CSV files are provided for users who prefer CSV over Excel files.
Section_names.pdf which shows the changes in the Broadbalk sections over time.
description: Wheat and straw yields are at 85% dry matter. Straw yield is that part of the straw cut by the combine harvester, and does not include the stubble or all of the chaff. Since 1980 straw yield has been recorded regularly for Section 1 and the 1st wheat in rotation only each year, with some other sections in other years. In fallow years the plots were cultivated to kill weeds. No N fertilizer was applied, but FYM and PKNaMg applied as usual. Fallow (no crop) yields are shown as blank cells. 
Strip 21 was also known as 2.1, 2a and 2A; strip 22 was also known as 2.2, 2b and 2B. By convention, the year is that of harvest (not sowing).
description: Yields of grain and straw are from the BKYIELD_R85 datasets in the e-RA database. Treatment details were taken from the Rothamsted Yield Books, published each year with details of each experiment. 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. Once the data were entered into e-RA, they were independently back-checked against the original data sheets. We thank the many other Rothamsted staff who have been involved in the production of this data, including farm staff, field recorders, laboratory staff and data recorders, too numerous to mention.