Corn Yield Response to Residual Forage Crop Rotation and Manure Amendment Effect in Potato Rotations.
Timothy Boring, Sieglinde Snapp, Richard Leep, and Ronald Gehl. Michigan State Univ., 286 Pssb, East Lansing, MI 48824
Accurate prediction of multiple-year N availability from organic sources is difficult and can complicate nitrogen management for producers using these sources. Manure applications and forage rotations require an understanding of N dynamics over both the short and long term in order to appropriately devise fertility recommendations. The objective of this 5-year study was to use corn yield and soil N monitoring to evaluate long-term nutrient availability from rotational systems on an irrigated Alfisol in central Michigan. All crop sequences were grown with either annual liquid dairy manure at 12,260 L ha-1 or conventional mineral fertilizer application from 2002 to 2004. Mineral fertilizer was used to supplement manure treatments to ensure balanced fertility levels across treatments. Potatoes were preceded by one-year crops of corn, alfalfa, and sudex and two-year stands of alfalfa and festulolium. Corn was planted across all treatments in 2005 and 2006 with no applied fertilizer or manure. Grain yield, moisture and test weight were measured for response to residual N. Results in 2005 indicated significant crop rotation and manure amendment effects on corn grain yield, moisture, and test weight. Treatments with a history of manure application had increased yield, decreased moisture, and increased test weight than treatments with only mineral fertilization. Corn preceded by alfalfa had increased yield, decreased moisture, and increased test weight compared with any other crop rotations. The multiple-year nutrient availability observed in rotation systems with organic nutrient sources indicates revised fertilizer recommendations may be necessary to better utilize existing soil nutrients in these systems.