Initial calibration and correlation of inorganic‐phosphorus soil test methods with a bahiagrass field trial

Abstract

Abstract In recent field studies, bahiagrass (Paspalum notatum L.), a major forage crop in Florida, did not respond to added P fertilizer even though preplant Mehlich‐1 (M‐1) soil test indicated very low extractable P (<10 mg/kg). Selected extractants for soil P were statistically compared to improve the predicted need for P fertilization. A separate field study was used to provide yield and nutrient uptake data. The field experiment was arranged in a randomized complete block design with four replications on a Myakka fine sand (hyperthermic aeric Haplaquod). Plots were fertilized in March of 1989 and 1990 with 0,17, 34, 51, and 68 kgP/ha. Soil samples were taken from the Ap horizon (0 to 15 cm) in January, 1990. Extractants included iron hydroxide impregnated filter paper (Pi), anion exchange resin (trimethyl benzyl ammonium active group), M‐1, Mehlich‐3 (M‐3), and water. There was a high correlation between Pi and the resin procedures (r2 = 0.96). These methods gave higher extractable P values compared ...