The Electronic Rothamsted Archive
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This document gives a description of the Park Grass Experiment and the data which are available. You are also able to request data.
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The Park Grass experiment is an experiment on grassland laid down at Rothamsted in 1856 in order to study the effects of applying different fertilizers.
Since then, plots have been reduced in size and subdivided for different liming treatments. On some plots there have also been changes in the fertilizer treatment. However the treatment on some subplots has remained unaltered. 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.
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.
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.
A summary of the current treatments of the plots is given below:
| Plot | Treatment |
| 1 | N1 |
| 2-1 | None until 1995, K from 1996 |
| 2-2 | None |
| 3 | None |
| 4-1 | P |
| 4-2 | N2 P |
| 6 | N1 P K Na Mg |
| 7 | P K Na Mg |
| 8 | P Na Mg |
| 9-1 | P K Na Mg (N2 until 1989) |
| 9-2 | N2 P K Na Mg |
| 10 | N2 P Na Mg |
| 11-1 | N3 P K Na Mg |
| 11-2 | N3 P K Na Mg Si |
| 12 | None |
| 13-1 | 35 t/ha FYM and fishmeal to supply 63 kg/ha N, each once in four years until 1994 |
| 13-2 | 35 t/ha FYM and fishmeal to supply 63 kg/ha N, each once in four years |
| 14-1 | P K Na Mg (N2* until 1989) |
| 14-2 | N2* P K Na Mg |
| 15 | P K Na Mg |
| 16 | N1* P K Na Mg |
| 17 | N1* |
| 18 | N2 K Na Mg |
| 19 | 35 t/ha FYM every fourth year |
| 20 | 35 t/ha FYM every fourth year, in other years 30 kg/ha N as nitrate of soda, 15 kg/ha P and 45 kg/ha K |
N1, N2, N3 sulphate of ammonia supplying 48, 96, 144 kg/ha N
N1*, N2* nitrate of soda supplying 48, 96 kg/ha N
P 35 kg/ha P as superphosphate
K 225 kg/ha K as sulphate of potash
Na 15 kg/ha Na as sulphate of soda
Mg 10 kg/ha Mg as sulphate of magnesia
Si 450 kg/ha of silicate of soda
The a,b and c subplots have lime applied as necessary to maintain pH 7,6 and 5 respectively and the d subplots have no lime applied.