Effect of co‐application of microbial biostimulant with different phosphorus rates in potatoes

Optimizing phosphorus (P) management in potato ( Solanum tuberosum L.) production while minimizing environmental impacts remains a significant challenge, particularly in sandy soils. This 2‐year field study evaluated the effects of microbial biostimulants and varying P rates (0–112 kg P ha −1 ) on potato yield, quality, P use efficiency, and soil P availability in Florida's sandy soil. The study employed a split‐plot design with six P rates as main plots and biostimulant application as subplots. Results revealed that total and marketable tuber yields increased significantly with P application, with the highest responses observed at 90 kg P ha −1 . Marketable yield improved even in soils testing high in extractable P, underscoring that the extractable soil P does not reliably indicate plant‐available P during early growth. P fertilization had minimal effects on specific gravity but increased pick‐outs at higher rates. However, biostimulant application with the tested product did not significantly enhance tuber yield, quality, or P use efficiency across any P rate. P use efficiency indices declined with increasing P rates. The study revealed that while P fertilization remains crucial for potato production in sandy soils, the effectiveness of the microbial biostimulant may be limited under current management practices. These findings suggest the need for refined P management strategies that account for seasonal variations in soil P availability and site‐specific environmental conditions to optimize potato production while improving P use efficiency.