|COULTER, JEFF - University Of Minnesota|
|YOST, MATT - University Of Minnesota|
|SHEAFFER, CRAIG - University Of Minnesota|
|KAISER, DAN - University Of Minnesota|
Submitted to: Forage Focus
Publication Type: Trade Journal
Publication Acceptance Date: 11/21/2011
Publication Date: 12/15/2011
Citation: Coulter, J., Yost, M., Russelle, M.P., Sheaffer, C.C., Kaiser, D. 2011. Accounting for alfalfa N credits increases returns to corn production. Forage Focus. December 2011. p. 20.
Technical Abstract: Guidelines are relatively consistent across the Upper Midwest regarding the N benefit of alfalfa to the following grain crops. With higher corn yields and prices, however, some growers have questioned these guidelines and whether more N fertilizer is needed for first-year corn following a good stand of alfalfa. We conducted two sets of trials in first-year corn after alfalfa on farms in southern and central Minnesota from 2008 to 2010. Our conclusions: 1) in most situations growers can maximize profitability by not applying N to first-year corn grain after alfalfa on medium- to fine-textured soils with good alfalfa stands; 2) corn silage may need a small amount of N (30 lb N/acre or less) to maximize economic return; and 3) fall alfalfa regrowth and tillage timing did not affect the responses of first-year corn to N fertilizer, thus growers should consider harvesting fall regrowth prior to stand termination if weather conditions permit. A small amount of N fertilizer may be needed to optimize corn grain yield in certain situations, such as: 1) on heavy, poorly drained, wet soils with low oxygen levels where N mineralization is slowed or denitrification occurs between the time of alfalfa stand termination and early-season corn growth; and 2) on sandy soils where rainfall between the time of alfalfa stand termination and early-season corn growth stimulates leaching of N.