Phosphorus Dynamics On Swine Manure Applied Fields.

Soluble phosphorus is causing Eutrophication in Grand Lake St. Marys and Lake Erie in Ohio.  Our objective was to study the effect of tillage, cover crops, and swine manure application on soluble reactive phosphorus (SRP) leaching and surface runoff. Using a randomized complete block design at South Center, Piketon, Ohio on an Omulga silt loam soil; swine manure (sm) was applied to 21 plots with seven treatments (3x replications) using 30 by 50 feet lysimeters.  Treatments included conventional tillage in corn soybean (CTCS) rotation and no-till (NTCS) both with chemical fertilizer (cf), NTCS with 6,600 and 8,600 gallons sm, and NTCS with cereal rye cover crop (cc), 6.6K and 8.6K sm. Swine manure was broadcast in early spring in 2010 and 2011 and surface runoff and leachate collected from June 2010 through September 2012.  SRP leachate levels on NTCS with cc applied with 6.6K and 8.6K sm (.50 mg/l and 0.75 mg/l) and CTCS (.55 mg/l) were significantly different than NTCS with cc and cf (11 mg/l) and NTCS cf (3.5 mg/l), and NTCS 6.6 and 8.6 sm (2.0 mg/l) in May 2010.  SRP leachate levels on NTCS with cc applied with 6.6K and 8.6K sm were zero compared to NTCS cf (55 mg/l) and NTCS 8.6 and 6.6 sm (35 and 24 mg/l), and NTCS cf (26 mg/l) in November 2010.  The NTCScc rotation significantly reduced SRP with swine manure leachate runoff compared to other treatments without cc.  NTCScc rotation also reduced cf leachate runoff compared to other treatments.