393-2 Phosphorus Loss Through Subsurface Tile Drainage During Eleven Years of Manure or Fertilizer Application for Corn and Soybean.

See more from this Division: S11 Soils & Environmental Quality
See more from this Session: Phosphorus Fate In Long-Term Fertilized/Manured Soils
Wednesday, October 19, 2011: 1:20 PM
Henry Gonzalez Convention Center, Room 212A
Share |

Mazhar U. Haq1, Antonio P. Mallarino1, Rameshwar S. Kanwar2, Pederson H. Carl2, Pecinovsky T. Kenneth3 and Matthew J. Helmers2, (1)Agronomy, Iowa State University, Ames, IA
(2)ABE, Iowa State University, Ames, IA
(3)Northeast Iowa Research Farm, Iowa State University, Nashua, IA
Phosphorus loss through subsurface drainage can be an important mechanism of P delivery to water resources. A study was conducted during 11 years in a typical Northeast Iowa soil to determine impacts of liquid swine manure or fertilizer P application for corn and soybean on soil P and P loss with tile drainage. Three nutrient management systems that involved chisel-plow tillage were manure applied every year for both crops of a corn-soybean rotation or continuous corn based on N need or N removal with grain harvest (MN2Y), N-based manure only for corn of a corn-soybean rotation (MNC), and N-P fertilizer for both crops of a corn soybean rotation according to Iowa recommendations (FNP). A fourth system that involved no-till management for a corn-soybean rotation was N-based manure only for corn (MNCNT). Swine manure always was injected, and fertilizer P was broadcast and incorporated into the soil. Profile soil-test P (STP) was measured to 120 cm. The STP for all systems was greatest in the 0-15 cm soil layer, and decreased abruptly to background initial levels below 15 cm for all systems. Topsoil STP (15-cm depth) by the last year of the study was 96 and 19 mg P kg-1 for MN2Y and FNP, and was intermediate but highly variable for MNC and MNCNT. A soil P saturation index (15-cm depth) was well correlated with STP across manure and fertilizer management systems. The mean annual P loss was highest for MN2Y (17 g P ha-1), intermediate for MNC and MNCNT (12 g P ha-1), and lowest for FNP (4 g P ha-1). Annual application of N-based manure greatly increased STP and P loss with tile drainage compared with fertilizer P-based application. Effects of N-based manure application for corn of corn-soybean rotation with or without tillage resulted in intermediate STP and P loss.
See more from this Division: S11 Soils & Environmental Quality
See more from this Session: Phosphorus Fate In Long-Term Fertilized/Manured Soils