Since 1965 most of the plots have been divided into four subplots, one of which remains unlimed and the other three of which receive varying quantities of lime every four years.
The plots are cut in June or July and made into hay. In the early years the aftermath was grazed by sheep but since 1875 a second cut has usually been made in the autumn or winter. Before 1960 yields of hay were recorded and dry matter yields estimated by determining the percentage dry matter content of samples of hay. The second crop was usually weighed green although it was sometimes made into hay. Since 1960 yields have been calculated from the weights of produce from sample strips immediately after cutting by a forage harvester. Consequently recorded yields of dry matter are now larger than previously as fewer losses occur. At the same time, the area harvested to determine yield is much smaller than it was before 1960 when the entire produce of each plot was weighed.
The first liming of some subplots took place in 1881, 1883 and 1887. Regular liming of half of some of the plots every four years began in 1903 and the scheme was extended in 1920.
Studies have also been made of the botanical composition of the plots both through visual surveys and by looking at the percentage contribution to the hay made by the various species. Often just a partial separation into grasses, legumes and other species was made. A recent research project in collaboration with the Open University and Imperial College has been looking at changes in the botanical composition of the Park Grass plots.
Chemical analyses of the crops and soil have also been carried out and physical samples of crops and soils have been preserved.
For further information and assistance, please contact the e-RA curators, Sarah Perryman and Margaret Glendining using the e-RA email address: firstname.lastname@example.org