COMPARISON OF SULFUR UPTAKE BY OILSEED RAPE AND THE SOIL SULFUR STATUS OF 2 ADJACENT FIELDS WITH DIFFERENT SOIL SERIES

At Woburn Experimental Farm (SE central England) sulphur (S) deficienc y symptoms occurred in a winter oilseed rape crop grown in Lansome fie ld on soil of the Cottenham series, but not on the Blithe series soil in the adjacent Mill Dam Close field. At maturity, the two crops produ ced a similar amount of dry matter but seed yield and harvest index we re significantly less in Lansome. Total S uptake of the crop in Lansom e was less than half of that in Mill Dam Close, which was similar to t he amount normally found in a S sufficient crop. Both soils are of lig ht texture (loamy sand and sandy clay loam for the Cottenham and Blith e series, respectively), and there was little difference in the extrac table S concentration in the topsoils between the two fields. However, more extractable S was found in the subsoil of Blithe series, because it contains more free Fe and Al oxides and has a lower pH. These resu lts show that any evaluation of the soil S supply needs to take into a ccount the pool of available S in the subsoil.