Changes in Soil Test Phosphorus in Continuous Rain-Fed Cotton

Soil testing is key to proper phosphorus (P) management for crop production across the Mid-South and is essential for economic fertilizer applications and reduced potential for P buildup in the soil and in nearby streams.  A multi-year field study was established at the Tribbett Satellite Farm of the Delta Research and Extension Center in a rain-fed (non-irrigated) environment and continuous cotton production.  Initially, 0, 20, 40 and 60 lb P/acre was fall- applied with and without AVAIL™ Phosphorus Enhancer.  The P applications were made for four years (2010-2013) to build up P levels and then no fertilizer P was applied in subsequent years (2014-2016).   Seedcotton and lint yields have been measured each year along with soil test P.  The 4x2 factorial arrangement of P rates (4) plus AVAIL (2) was included in a randomized complete block design with six replications.  Yield data and soil test data will be examined across all years of the study.