Potato yield and tuber quality did not respond to phosphorus fertilization of soils testing high in phosphorus content

Phosphorus (P) fertilization studies were conducted on four commercial farms and at the University of Florida Institute of Food and Agricultural Sciences Hastings Research and Education Center in Hastings. All sites were in the potato (Solanum tuberosum) production area of northeastern Florida. Preplant Mehlich-1 soil test P was very low at one commercial site and very high at the other four sites. The yield of marketable size A tubers, the desired tuber category, did not respond to P fertilization from 0 to 66 lb/acre (74.0 kg(.)ha(-1)) of P at any site. The average yield across all sites was 324 cwt/acre [16.2 ton/acre (36.3 t(.)ha(-1))]. Leaf-P concentration at midseason did not respond to P fertilization. Leaf-P concentration averaged 0.38%, which was sufficient for potato. Potato tuber specific gravity averaged 1.075 and responded slightly to P fertilization only at one site.