Dataset: Park Grass Yields and Fertilizer Treatments 1965-2024

In 1965, a new design, "Third Design Period", was introduced on Park Grass for most plots, with a new soil liming regime, having four sub-plots per each plot to provide soil at (a) pH 7, (b) pH 6, (c) pH 5 and (d) un-limed. This dataset contains the annual yields of hay (t/ha), for both the 1st and 2nd cuts, harvested from Park Grass Hay Experiment from 1965 to 2024 inclusive. Details of the fertilizer, lime treatments and harvest dates are also included. Yields are provided for all fertiliser treatment plots and sub-plots (except for plots 5, and 6c & 6d, which are used for micro-plot experiments). 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 new dataset also introduces an additional plot identification number, "new_plot_id" (as well as adding another years data for 2024, to the previous 1965-2023 dataset). This new plot id number uses a new naming convention assigned retrospectively to all plots since the start of the experiment in 1856. It is intended to show the provenance of the treatments of the plots using ' \ ' and '.' to indicate significant changes, where ' \ ' indicates a liming change and '.' indicates a plot-split for a fertilizer modification. For example, original plot number id., 7\1a now also has the new plot id., 7.1\L\a, where 7.1 indicates it has been split, for a new fertilizer treatment, and \L\a indicates the changes in liming it has undergone (where L a indicates a limed half pre-1964 and a indicating lime to pH 7 from 1965. See Technical information for a further explanation (on this dataset webpage).

<b>NB. the change in harvest method in 1960 means recorded yields of dry matter are larger than previously as fewer losses occur. See Additional Information (on this dataset webpage) for a conversion factor to use for post-1960 data for cut 1 to give yield values equivalent to pre-1960 values and see Methods for the harvesting details (on this dataset webpage).</b>

Plot 12 and 15 did not join this new liming scheme until 1976.