Nitrogen Dynamics On Swine Manure Applied Fields.

Soluble nitrogen (SN) is a major issue with hypoxia in the Scioto and Ohio River.  Our objective was to study the effect of tillage, cover crops, and swine manure (sm) application on SN leaching and surface runoff. Using a randomized complete block design at South Centers, Piketon, Ohio on an Omulga silt loam soil; 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.  SN leachate levels on NTCScc applied with cf and 6.6K  and 8.6K sm (2.5, 3.0, 5.0 mg/l) were significantly different than NTCS applied cf (8.0 mg/l) and NTCS 6.6 and 8.6 sm (9.0 and 10.0 mg/l) compared to CTCS cf (16 mg/l) in March 2011.  SN leachate levels on NTCScc applied with 6.6K and 8.6K sm and cf were 2.5-2.8 mg/l compared to NTCS 6.6 and 8.6 sm (7.5 and 8.0 mg/l) and NTCS cf (9.0 mg/l) compared to CTCS cf (10 mg/l) a week later in 2011.  The NTCScc rotation significantly reduced SN with swine manure leachate runoff compared to other treatments without cc.  NTCScc rotation also reduced commercial fertilizer SN leachate runoff compared to other treatments.