DOI: 10.23637/rpg5-yields1903-1964-01
title: Dataset: Park Grass Hay Yields, Fertilizer and Lime Treatments 1903-1964

description: This dataset contains the yields of hay (t/ha), for both the 1st and 2nd cuts, harvested from Park Grass Hay Experiment since 1903-1964. Details of the fertilizer, lime treatments and harvest dates are also included. Originally one plot per treatment, in 1903, most plots were split into two to test the effects of liming, as acidity had built up with fertilizer use, with one half limed with chalk (L) and the other half left un-limed (U). In 1920 the remaining plots (14, 15 and 17) were split in half also, to join the liming scheme. Three other plots (18, 19 and 20) were split to three to receive light lime (LL), heavy lime (HL) and un-limed (U). Yields are provided for all fertiliser treatment plots and sub-plots. Yields are expressed as t/ha at 100% dry matter. Variations in yield reflect the various fertilizer treatments and liming regimes, as well as the local weather and atmospheric inputs. This data set is followed by that for 1965-2018 and so includes plot numbers (subsequent plots) from that later design-period to provide continuity between datasets.
description: This experiment tests the effects of inorganic fertilizers, organic fertilizers and soil pH (which varies on sub-plots as a result of liming) on yields of hay. See Second Design Period 1903-1964 for detail. Until 1959, the yields were estimated by cutting and weighing the whole sub-plot produce. Since 1960, yields were estimated from strips cut from the centre of each plot with a forage harvester (in the dataset, the forage harvester weight is converted using an equation from Bowley et. al and both values are provided). After the first cut in mid-June the remainder of each plot is mown and made into hay, continuing earlier management and ensuring return of seed. For the second cut, the whole of each plot is cut with a forage harvester.
description: An Excel file, rpg5_yields_1903-1964_01.xlsx, contains Park Grass fertilizer and lime treatments and the yields for the 1st and 2nd cuts. Frictionless CSV files are provided for users who prefer CSV over Excel files.
description: Hay yields have been recorded every year since the Park Grass experiment began, with the first harvest in 1856. Dried samples have also been kept since 1856 and these are preserved in the Rothamsted Sample Archive.
description: Individual plot yields are derived from the PGHAYEQUIV dataset in the e-RA database and were checked with the published yields in the annual Rothamsted Yield Books. 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. Park Grass was initiated to investigate the ways of improving the yield of hay by the application of inorganic fertilizers and organic manure. With time, the soil became more acidic and in 1903 plots had been halved and the effects of lime tested. From 1965 a new liming regime was initiated with four sub-plots, three receiving lime to maintain soil pH (0-23cm depth) at pH 7, 6, and 5 on sub-plots a, b and c. Sub-plot d does not receive any lime. These later yields are available in the dataset 'Park Grass Hay Yields, Fertilizer and Lime Treatments 1965-2018'.

The change in harvest method in 1960 means recorded yields of dry matter are larger than previously as fewer losses occur. The previous harvest method estimated yield by weighing the produce from the whole field. See reference by Bowley et al (2017).