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This document gives a description of the Broadbalk Experiment and the data which are available. You are also able to request data.
The first experimental crop of wheat was sown on Broadbalk in 1843 and harvested in 1844. The aim of the experiment was to test the effect of different organic manures and inorganic fertilizers on the yield of winter wheat. For the first few years the treatments varied somewhat but in 1852 a permanent scheme was established which has continued, with some minor modifications, to today.
The experiment has had three main phases: (Click on a plan to display an enlarged version ).
1. 1844-1925 Wheat was grown continuously, apart from occasional fallowing of parts of the field
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2. 1926-1967 The field was divided into five strips, which were fallowed in turn. In 1956 Section I was divided into two; IA was assigned to continuous wheat with weedkillers as required but no fallows, while IB continued in the five year cycle. In 1963 Section V was divided into two; VB was assigned to continuous wheat with weedkillers, while VA continued in the five year cycle.
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3. 1968- The field is now divided into ten sections, on some sections wheat is grown continuously, while on others it is grown in rotation with other crops.
Grain and straw yields are recorded each year. Other data collected include observations of weeds, pests and diseases and the results of chemical analyses of crops and soils. Physical samples of crops and soils have been preserved.
A summary of the current treatments of the plots is given below:
| 1 | D N4 P K |
| 3 | None |
| 5 | P K Mg |
| 6 | N1 P K Mg |
| 7 | N2 P K Mg |
| 8 | N3 P K Mg |
| 9 | N4 P K Mg |
| 10 | N2 |
| 11 | N2 P |
| 12 | N2 P Na |
| 13 | N2 P K |
| 14 | N2 P 30 kg/ha Mg as kieserite |
| 15 | N5 P K Mg |
| 16 | N6 P K Mg |
| 17 | Even years: N1 in autumn, N3 in spring, 1/2 (P K Mg) |
| Odd years: N3 in spring, 1/2 (P K Mg) | |
| 18 | Even years: N3 in spring, 1/2 (P K Mg) |
| Odd years: N1 in autumn, N3 in spring, 1/2 (P K Mg) | |
| 19 | None (Castor meal to supply 96 kg N until 1988) |
| 20 | N2 K Mg |
| 21 | D N2 |
| 22 | D |
N1,N2,N3,N4,N5,N6 48, 96, 144, 192, 240, 288 kg/ha N as 'Nitram' (34.5% N)
P 35 kg/ha P as triple superphosphate
K 90 kg/ha K as sulphate of potash
Na 55 kg/ha Na as sulphate of soda
Mg (except Plot 14) 35 kg/ha Mg every third year as kieserite
D 35 t/ha Farmyard manure
The varieties of wheat grown on Broadbalk are as follows:
The most important change was in 1968 when shorter-strawed varieties were introduced. This led to an increase in grain yields and a decrease in straw yields. Squarehead's Master was grown on parts of some plots between 1987 and 1990, enabling a comparison to be made.