Dataset that accompanies a research paper entitled, "Experimental evidence that poor soil phosphorus (P) solubility typical of drylands due to calcium co-precipitation favors autonomous plant P acquisition over collaboration with mycorrhizal fungi" published in Soil Biology and Biochemistry September 28, 2024. Files include a readme file, bioassay datasets, and the respective R script for analyzing the individual data files.Results are relevant to arid and semiarid mixed-grass prairie ecosystems with calcareous and alkaline subsoils, especially sites with soils of Eapa loam soil series, frigid Aridic Argiustolls or Mollisols. The focal system was of northern mixed-grass prairie vegetation near Miles City, Montana which is in eastern Montana, USA (soil collection area: 46.304583, -105.978050, elevation 849 m). The study consisted of two pot experiments including: 1) calcium carbonate addition and incubation experiment and 2) calcium carbonate addition and arbuscular mycorrhizal inoculant experiment. The experiments were designed to improve understanding effects of calcium carbonate on soil pH and available phosphorus (via. co-precipitation of calcium and phosphorus) in the absence of plants and mycorrhizal fungi (#1). The other experiment utilized eight plant species, calcium carbonate additions, and mycorrhizal inoculant to discern modes of phosphorus acquisition by plants (i.e. root P mining versus mycorrhizal collaboration; #2) over a soluble phosphorus gradient. Pot experiments utilized completely randomized designs. #1 was a single factor experiment with four calcium carbonate addition levels. #2 was a three factor experiment with eight plant species, four calcium carbonate levels, and a mycorrhizal inoculant treatment. Data include soil pH, soil nutrients, shoot phosphorus, shoot manganese, mycorrhizal responsiveness (i.e. Cohen's D), total plant biomass, shoot biomass, and root mass ratio.Additional details can be found in the readme file, manuscript, and manuscript's supplement.