Compared to other crops, potatoes have a low phosphorus (P) use efficiency (PUE). This characteristic, combined with low soil P availability, can impact the yield. The common method to verify the availability of a nutrient to the crops is through soil testing. In 2012, Florida transitioned from Mehlich-1 (M1) to Mehlich-3 (M3) for soil P recommendations; however, the updated M3 guidelines indicate that no additional P should be applied. Many other studies have confirmed that yield responses to P fertilizer continue to be observed. The objective of this study was to identify a P fertilization strategy involving multiple applications and using two different sources of P-fertilizer to increase potato yield and PUE. A field experiment with nine treatments and four replications was established in Hastings Agricultural Extension Center-HAEC/IFAS/UF in three areas with different soil P levels, 118, 179, and 219 mg/kg P (M3). These areas were cultivated with the potato cultivar Atlantic during the 2024 and 2025 growing seasons. A single rate of 120 lb/ac of P2O5 of granular phosphate was applied at 30 and 15 days before planting, at planting, and at 25 and 50 days after planting (DAP). The same P-rate was also split into 40 and 60 lb/ac of P2O5 applied at 0, 25, 50 DAP, and 0 and 25 DAP, respectively. In addition, a liquid P-source was applied using this same split application and times. At the harvest, tubers were graded according to USDA size standards, and specific gravity, total, and marketable yields were measured. To calculate PUE, the total yield was divided by the initial soil P content plus the applied P fertilizer. There were no significant differences in total yield as a function of the application timing within each area, as well as for specific gravity. The PUE significantly decreased with the increase in soil initial P level. In 2024, the area with the lowest initial soil P concentration had the highest yield, producing 332 cwt/ac, while the area with the highest initial P concentration produced 268 cwt/ac of potatoes, and the medium initial soil P area produced 324 cwt/ac. In 2025, the area with the highest initial soil P concentration produced 332 cwt/ac, while the lowest area produced 327 cwt/ac, and the medium initial soil P area had the lowest yield, producing 308 cwt/ac. The results of this study may support updating Florida’s recommendation guidelines to enhance P-fertilizer use efficiency and crop yield.
