This document is the Phosphorus Index Test Form (SL394), one of the Soil Testing Information Sheets (Submission Forms) used by the UF/IFAS Extension Soil Testing Laboratory. The sheet provides details about how to collect samples and testing fees.

Impact of Phosphorus on Water Quality

Rao Mylavarapu

SL-275 highlights the role of phosphorus, interactions with the environment, and its potential impact on water quality. It is intended to serve audiences such as high school students, farmers, and the general public seeking information on the causes and mechanisms of potential phosphorus effects on water quality. Includes references.

Iron Oxide Strip as an Innovative Diagnostic Tool for Soil Phosphorus Management

Lilit Vardanyan andVimala D. Nair

Phosphorus (P) is essential for plant growth and productivity. Excessive application of P fertilizers has contributed to environmental degradation through runoff and leaching into waterways. Traditionally, the Mehlich 1-P and Mehlich 3-P soil tests have been used widely to guide fertilizer recommendations in Florida and many other regions. However, these may provide inaccurate estimates of plant-available P, especially in soils with diverse mineralogy or strong P-sorption capacity. This can result in suboptimal fertilization practices. Unlike standard soil tests, which rely on chemical extractants that may mobilize both labile and non-labile forms of P, the iron oxide strip P (FeO-P) method targets the fraction most relevant to plant uptake, offering a more reliable indicator of P availability. FeO-P mimics the absorptive behavior of plant roots to determine actual crop nutrient demand, providing an improved diagnostic tool for both agronomic and environmental applications.

Rethinking the Role of Nitrogen and Phosphorus in the Eutrophication of Aquatic Ecosystems

Ashley Smyth, H. Dail Laughinghouse IV, Karl Havens, andThomas Frazer

Nitrogen and phosphorus are two nutrients that are essential for the growth and survival of plants and animals but are often present in short supply. Both nitrogen and phosphorus are applied regularly through fertilizer to increase the yield of crops needed to feed human populations and for residential and commercial landscaping purposes. This publication contains information for stakeholders, students, scientists, and environmental agencies interested in understanding how nitrogen and phosphorus affect water resources. Major revision by Ashley Smyth, H. Dail Laughinghouse IV, Karl Havens, and Thomas Frazer; 5 pp.

Phosphorus

Publications

Best Management Practices in the Everglades Agricultural Area: Controlling Particulate Phosphorus and Canal Sediments

Parameters for Site-Specific Soil Phosphorus Loss Modeling from Soil Test Data

Best Management Practices in the Everglades Agricultural Area: Fertilizer Spill Prevention

Particulate Phosphorus in the Everglades Agricultural Area: II—Transport Mechanisms

Particulate Phosphorus in the Everglades Agricultural Area: I—Introduction and Sources

Nutrient Mass Budget—The Case of Florida Watermelon Phosphorus Export

Soil-Test-Based Phosphorus Recommendations for Commercial Agricultural Production in Florida

Economic Analysis of Water Treatments for Phosphorus Removal in Florida

Phosphorus Index Test Form

Impact of Phosphorus on Water Quality

Iron Oxide Strip as an Innovative Diagnostic Tool for Soil Phosphorus Management

Rethinking the Role of Nitrogen and Phosphorus in the Eutrophication of Aquatic Ecosystems

Driving Innovation in Phosphorus Sustainability Across South Florida

Phosphorus Management in Florida Must Be Soil-Specific

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