Jason Daniel Clark1, Earl Creech2, Corey Ransom3, Ralph Whitesides2 and Grant E. Cardon2, (1)Utah State University, Falcon Heights, MN (2)Utah State University, Logan, UT (3)Plant Soils and Climate, Utah State University, Logan, UT
Glyphosate containing herbicides are a common and highly effective method to terminate alfalfa stands. With the development of glyphosate resistant alfalfa, this tool is no longer an option. The purpose of this research was to determine the best combination of termination methods to rotate from glyphosate resistant alfalfa into silage corn. Studies were conducted on a Trenton Silty Clay Loam in Cache Junction, Utah and a Layton Loamy Fine Sand in Cornish, Utah to determine the effect of tillage type and timing (fall conventional till, spring conventional till, fall strip-till, spring strip-till, and no-till), herbicide timing (fall, spring, in-crop, and a control), and N rate (0, 56, 112, and 224 kg N ha-1) on the amount and timing of alfalfa re-growth, available N, corn emergence, and subsequent yield and quality of silage corn. There was a significant interaction between tillage type and timing and herbicide timing. The combinations that consistently performed the highest were those that contained fall conventional tillage, spring conventional tillage and/or fall or spring herbicide timing. Followed by the combinations containing fall strip till, spring strip till, no-till with in-crop herbicide timing. The lowest yields were the control plots unless they received the spring conventional tillage treatment. Fertilizer rate did not significantly affect yields at either site.