Phosphorus Placement in Reduced Tillage Systems.

No-tillage and reduced tillage systems cause significant Phosphorus (P) management concerns due to increased P concentration at the soil surface leading to stratification of P.  Several factors contribute to this problem such as traditional broadcasting P fertilizer without incorporation and P uptake by plants followed by decomposition and release of P into the surface of the soil.  Deep banded P has been used to reduce P stratification by placing the P fertilizer deep in the soil.  The level of response from deep banding is likely influenced by the severity of the stratification, initial soil test P levels, and rainfall patterns.  Much of this research has been conducted in the eastern cornbelt where rainfall is adequate.  The objectives of this study are to: 1.) Determine if deep banding of P enhances availability as compared to surface broadcasting , 2.) Evaluate total P uptake differences from broadcast and deep band application of P, 3.) Observe starter responses to application with broadcast and deep band application.  This study was conducted at four sites across Kansas ranging from 44.2 to 99.6 cm mean annual precipitation (30 yr average 1971-2001).  Crops in this study included corn, soybean, sorghum, and wheat.  Phosphorus fertilizer was applied as broadcast, deep band, and combinations of each with starter.  Each site had well established P stratification with soil test P concentrations of 9.4 to 74.1 ppm in the 0 to 7.6 cm soil layer and 3.4 to 23.5 ppm in the 30.5 to 61 cm segment.  There were not significant differences in the method of application or in starter application in 2006 and 2007.  Data from this trial is inconsistent, but some specific trends appear to follow basic plant nutrition principles.  This work, conducted in a more arid climate should provide important information to complement previous studies.