Model estimates of topsoil nutrients [Countryside Survey]

Topsoil nutrient data - total nitrogen (N) concentration (%), C:N ratio and Olsen-Phosphorus (mg/kg). Data is representative of 0 - 15 cm soil depth. Cores from 256 1km x 1km squares across Great Britain were analysed in 2007. For total N concentration (and therefore C:N ratio), a total of 1024 cores were analysed, and for Olsen-P, a total of 1054 cores were analysed. See Emmett et al. 2010 for further details of sampling and methods (http://nora.nerc.ac.uk/id/eprint/5201/1/CS_UK_2007_TR3%5B1%5D.pdf). Estimates of mean values within selected habitats and parent material characteristics across GB were made using Countryside Survey (CS) data from 1978, 1998 and 2007 using a mixed model approach. The estimated means of habitat/parent material combinations are modelled on dominant habitat and parent material characteristics derived from the Land Cover Map 2007 and Parent Material Model 2009, respectively. The parent material characteristic used was that which minimised AIC in each model (see Dataset Documentation). Please see Scott, 2008 for further details of similar statistical analysis (http://nora.nerc.ac.uk/id/eprint/5202/1/CS_UK_2007_TR4%5B1%5D.pdf). Areas, such as urban and littoral rock, are not sampled by CS and therefore have no associated data. Also, in some circumstances sample sizes for particular habitat / parent material combinations were insufficient to estimate mean values.