Recent changes in phosphorus and potassium fertilizer recommendations for Tomato, Pepper, Muskmelon, Watermelon, and Snapbean in Florida

Abstract

Mehlich‐I soil‐test calibrations and fertilizer recommendations were reviewed in light of the current literature. This review lead to 22 research/demonstration experiments conducted dominantly on cooperators’ fields. Crops included tomatoes (Lycopersicon esculentum Mill.), pepper (Capsicum annuum L.), watermelon (Citrullus lanatus Thunb., Matsum. and Nakai), muskmelons (Cucumis melo L. Reticulatus group), and snapbean (Phaseolus vulgaris L.). Soils selected for these trials included Ultisols, Spodosols, and Entisols. Minimum data collection at all sites included preplant soil tests (0‐ to 15‐cm depth) using the Mehlich‐I extractant, leaf tissue sampling (usually most recently‐matured leaf), and harvest data using USDA grading standards. Typically, four or five rates of P and/or K were used with four or five replications. The growers’ fertilization practices were also included in the trial. Additional yield samples were collected from outside the experimental area to verify yields obtained by the grower. Results from all experiments showed that yield response to added fertilizer optimized well before recommended rates were reached. The Mehlich‐I soil test identified soils with low fertility and critical values were found to be equivalent to, or lower than, published critical values for agronomic crops. The original Mehlich‐I soil test calibration for vegetables was set to preclude underfertilization, but with no field data to support the selection. Based upon the field work discussed herein, the Mehlich‐I soil test calibration for vegetables was lowered to agree with that for agronomic crops. This action appeared to be reasonable because the calibration for agronomic crops has been well documented and all experiments included in this paper support such a change. Extensive changes were also made in fertilizer recommendations for N, P, and K for vegetable production, including a recommendation for no fertilizer P and K when the Mehlich‐I soil test is interpreted as high or very high.

Notes

Florida Agric. Exp. Stn. Journal Series No. R‐02097

Corresponding author.

G.J. Hochmuth, Vegetable Crops Deparment., Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.