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

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.