An evaluation of the combined usage of separated liquid pig manure and inorganic fertiliser in nutrient programmes for winter wheat production

The effect of spring application of separated liquid pig manure (LPM) in combination with medium to high levels of inorganic nitrogen (N) to winter wheat was investigated in a field trial study at two sites in two successive growing seasons (2007-2008). The key crop parameters examined were crop N uptake (CNU), N use efficiency and grain yield. The LPM product (3.5-4.0 g/kg total N) was applied at three application rates: 15.30 and 45 m(3)/ha using a band spread application technique. The LPM was used in combination with reduced and recommended inorganic N levels; a zero N control was also included. Weather conditions in both seasons were similar with below average rainfall levels in spring followed by above average summer rainfall levels. The zero N control gave lowest CNU levels in both growing seasons (70-88 kg N/ha). Inorganic N application at the reduced and recommended N rates increased CNU levels by approximately 100 kgN/ha and 112 kgN/ha, respectively compared to the untreated control. Liquid pig manure application resulted in an additional crop uptake of 58 kgN/ha. Nitrogen use efficiencies for LPM ranged from 23 to 56% while inorganic N use efficiency levels were higher ranging from 58 to 73%. Lowest grain yield levels were measured from the zero N control (range 3.95-5.01 t/ha). The application of inorganic N increased grain yield levels by a minimum of 4.05 t/ha with LPM usage increasing grain yield levels by an additional 0.2-1.09 t/ha. This study showed that LPM could be successfully used in combination with inorganic fertilisers for the improved N nutrition of winter wheat in spring as part of an integrated nutrient programme. (C) 2010 Elsevier B.V. All rights reserved.