A tracer experiment was conducted in three study sites along a continental transect from arid to humid-temperate conditions in the Chilean Coastal Cordillera. The objective was to determine the short-term (<1 year) plant nitrogen (N) and potassium (K) acquisition from topsoil (A-Bw horizons), subsoil (Bw-BCw horizons), and saprolite (below BCw horizon). In February and March 2016, ¹⁵N (as Na¹⁵NO₃, 99 at%) and the K analogs rubidium (as RbCl) and cesium (as CsCl) were injected in three soil depths around the focal plants: Gutierrezia resinosa (H.&A.) B. in the northernmost site (arid shrubland), Aristeguietia salvia (C.) K.&R. in the intermediate site (mediterranean woodland), and Araucaria araucana (M.) K. in the southernmost site (temperate rainforest). The injection holes were drilled with an auger and the excavated soil material was collected to determine soil N, K, Rb, and Cs contents. In November 2016, shoot and root material of labeled and unlabeled plants was collected. The N, K, Rb, and Cs contents and the stable isotope ratios of δ¹⁵N (expressed as δ¹⁵N) in plant tissue were measured. The tracer recovery by plants was determined by the ¹⁵N enrichment and the shift of Rb and Cs contents normalized to the K content between reference plants and labeled plants. The data set contains the K, Rb, and Cs contents in soil.