Effect of phosphorus placement methods and rates on sugarbeet production under strip tillage in southern Idaho

Strip tillage usage is increasing in the sugarbeet production systems of the Pacific Northwest and research data to guide phosphorus placement options and application rate for those options need to be acquired. The effects of phosphorus application method (surface and subsurface band) and phosphorus application rate (0 to 230 kg P2O5 per ha) were evaluated in 2009 and 2010 on sugarbeet grown under strip tillage at the USDA-ARS Northwest Irrigation & Soils Research Laboratory at Kimberly, ID. The soil at the study sites was a Portneuf silt loam (coarse-silty mixed superactive, mesic Durixerollic Xeric Haplocalcids) that had low bicarbonate extractable phosphorus concentrations of 3.7 and 6.0 mg per kg in 2009 and 2010, respectively. In general, yields did not differ between phosphorus fertilizer application methods. Yields increased as phosphorus rate increased and were not maximized at the highest application rate applied in this study (greater than 230 kg P2O5 per ha). The harvested roots removed an equivalent of 14.3 percent of the applied fertilizer P and the entire plant extracted an equivalent of 22.7 percent of the applied fertilizer phosphorus. Research does not provide evidence that the current University of Idaho and Amalgamated Sugar Company phosphorus fertilizer recommendations should be changed for strip tillage regardless of the application methods used in this study