Understanding the effects of fertilizer addition and crop removal on long-term change in spatially-variable soil test P (STP) and soil test K (STK) is crucial for maximizing the use of grower inputs on claypan soils. Using apparent electrical conductivity (EC_a) to estimate topsoil depth (or depth to claypan, DTC) within fields could help capture the variability and guide site-specific applications of P and K. The objective of this study was to determine if DTC derived from EC_a could be used to improve P and K management for corn (Zea mays L.), soybean (Glycine max [L.]), and switchgrass (Panicum virgatum L.). Research was conducted at the University of Missouri’s South Farm Research Center in Columbia, MO from 2009 to 2016. Each year, corn, soybean, and switchgrass were grown on 16 plots (5.2 or 6.1 x 10 m) with DTC ranging from 0 to 94 cm. Soil EC_a data were collected in the spring of 2009 using a DUALEM-2S, and were calibrated to measured DTC. Surface (0-15 cm) soil samples for P and K were collected in the early spring of 2009, 2015, and 2016. Fertilizer was applied shortly after soil sampling in 2009 and 2015. Crop type did not influence results so data were analyzed across crops. Results showed that DTC affected STP, STK, P buffering index (PBI), and the amount of K₂O required to raise STK 1 kg ha^-1 (RK). The PBI increased from -16 to 12 kg P₂O₅ ha^-1 as DTC increased 0 to 44 cm. The RK increased from 1.75 to 11 kg K₂O ha^-1 as DTC increased from 0 to 40 cm. These relationships show that soils with shallow DTC likely need less fertilizer K, but more fertilizer P to achieve and sustain desired STP and STK levels, with the opposite occurring on soils with deeper DTC. Accounting for these differences could help guide variable-rate P and K applications, especially on fields with high variability of DTC. Therefore, accounting for DTC derived from EC_a could be used to enhance P and K management on claypan soils.