Alfalfa termination strategies to conserve soil moisture for no-till crop establishment

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Bullied, William John
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The ability of herbicides to terminate alfalfa in the fall or spring, and the feasibility of establishing wheat (cv. Roblin) and barley (cv. Bedford) was investigated. Parameters measured included soil moisture content (0-10cm), crop emergence, crop aerial biomass, alfalfa aerial biomass, and weed aerial biomass, spike density population, grain yield, and alfalfa regrowth. An additional fall alfalfa termination experiment was performed to evaluate herbicides and combinations of herbicides by measuring alfalfa regrowth in late May and late June of the following year. In the alfalfa ermination trials, termination (alfalfa termination with herbicides or tillage) x post-emergence herbicide application (dicamba 0.11 kg a.i. ha$\sp{-1}$ + MCPAK 0.42 kg a.i. ha$\sp{-1})$ interactions occurred for post-harvest alfalfa regrowth measurements in all 4 site-years, indicating that the post-emergence herbicide application was relatively more effective for the less effective initial termination treatments. In the herbicide evaluation trial, herbicides were evaluated for their ability to terminate alfalfa. Combinations of glyphosate and dicamba, and glyphosate and 2,4-D were found to suppress alfalfa to a greater extent than glyphosate applied alone. As well, 2,4-D was found to enhance the ability of clopyralid to suppress alfalfa. The moisture conservation experiments indicated that the potential exists to conserve soil moisture in the upper 30 cm soil profile, and also obtain a second cutting of alfalfa by utilizing herbicide to terminate alfalfa. (Abstract shortened by UMI.)