Data comprises patterns of diversity in a below-ground community of microarthropods (mites and collembola), measured during a nutrient (calcium and nitrogen) manipulation experiment, located at the Natural Environment Research Council (NERC) Soil Biodiversity Site in Sourhope, Scotland, UK. Data collected include abundance of microarthropods, and also microbial biomass carbon, soil respiration, wet pH using de-ionised water, soil loss on ignition, dry root biomass, total carbon and nitrogen content of soil and roots and soil moisture content. The data were collected as a component of the NERC Soil Biodiversity Programme, established in 1999 and centred upon the intensive study of a large field experiment located at the Macaulay Land Use Research Institute (now the James Hutton Institute)'s farm at Sourhope in the Scottish Borders. During this time, the site was monitored to assess changes in aboveground biomass production (productivity), species composition and relative abundance (diversity). Full details about this dataset can be found at https://doi.org/10.5285/fe2ba292-08b0-428c-8e27-8c851a4a8bbc