Long-term effects of lime and phosphorus application on soil extractable (Olsen) phosphorus differ between two arable UK soils

Liming induces several positive effects on soil processes, although the specific nature of these impacts is variable for some soil properties such as extractable soil phosphorus. The aim of this study was to analyse the long-term effect of liming on soil extractable phosphorus (Olsen P) concentrations, together with the corresponding effects on soil pH and P uptake by different crops. The soil and crop data were collected from two long-term experiment sites at Rothamsted Research with contrasting soil texture (Rothamsted and Woburn). Liming had significant effects on Olsen P on a silty loam soil at Rothamsted and a sandy loam soil at Woburn. At both sites where no P was applied the highest Olsen P value was in the lime control treatment (no lime) which was significantly greater than all of the liming treatments. Between 1968 and 1994 temporal changes in Olsen P were not affected by liming. The P removal in the grain showed significant differences in responses between crop species which indicates differences in the availability of P to a specific plant and the efficiency of P used by each crop accordingly. The contrasting results in this study indicate that liming can lead to differences in soil P availability, because of its effect on soil pH; also this effect can be partly explained by the differences in soil texture at each site. The amount of plant available P cannot be determined from Olsen P data only, and the P removal in grain should be taken into account in order to thoroughly evaluate P status of arable crops.