Soil Phosphorus Availability: Dr. Kamprath's Impact and Legacy.

Dr. Kamprath’s pioneering research on the measurement of soil phosphorus (P) availability and residual effects of applied P on availability and soil productivity in the 1970s is still relevant in today’s world of P scarcity and abundance paradoxes. He described how and why soils transitioned from sinks to sources of P with long term management, using Langmuir sorption techniques. We have built on this understanding in the last 10 years as the contextual paradigm has transitioned from a scarcity to an abundance discussion. This transition and the continuing eutrophication of Lake Erie, Chesapeake Bay, and Florida’s inland and coastal waters, has led to the use of soil P availability metrics to assess the potential for P enrichment of runoff. The foundations laid by Dr. Kamprath paved the way for our current efforts to quantify legacy P and future management challenges it presents. For instance, nitrogen-based application of manure, broadcasting of P in no-till systems, and adoption of conservation practices that trap P on the landscape have all contributed to in-field legacy P. In his quiet unassuming manner, Dr. Kamprath foresaw these consequences and challenged us to be innovative in finding solutions. This includes revisiting soil test P recommendations, accounting for the contribution of organic as well as inorganic soil P to long-term productivity, and recognizing that measures to address consequential tradeoffs should be part of future P-management planning strategies.