Link to additional data for Johnston et al (2017), European Journal of Soil Science.
Current design: Five year rotation of three years in arable crops or grass leys followed by two years of test crops (wheat and barley). Total of 80 plots divided into 5 blocks. Yields are recorded every year and one block is soil sampled each year. One block limed each year.
Strengths: Cropping data and yields available since 1938. Soil samples available from 1938, and then every 5 years since the mid-1950s. Only long-term ley-arable cropping experiment based on the sandy loam at Woburn. Provides a comparison with the two ley-arable experiments at Rothamsted.
Background: started in 1938 to compare the effects of rotations with or without grass or grass-clover leys on SOM and the yield of two arable test crops. Soils at Woburn that have been in continuous arable cropping since 1876 contain about 0.9 % C, and %C is still declining slowly; soils that have alternated between 3-year leys and 2-years arable since 1938 contain about 1.2 % C. Typically, where no fertilizer N is applied, grain yields of the first wheat test crop are greater following grass leys than in the continuous arable sequence because more N is available from the mineralisation of SOM. Following grass-clover leys, yield is increased further because of the extra N being made available from the breakdown of the leguminous residues. Following the leys, a larger yield is often achieved, with less fertilizer N, compared with continuous arable cropping.
Soil % Organic Carbon, 0-25cm 1938-2009
Soil % Nitrogen, 0-25cm, 1980-2008
Yields and estimates of carbon inputs to the soil, selected plots, 1938-2007, from Johnston et al, (2017)
Background taken from the Rothamsted Guide to the Classical Experiments 2006, page 41.