Glyphosate (N-(phosphonomethyl)glycine)-containing herbicides are a common and highly effective method to terminate alfalfa (Medicago sativa) stands. With the development and use of glyphosate-resistant (Roundup Ready®) alfalfa, this tool is no longer an option. The purpose of this research was to determine the optimal strategy to rotate from glyphosate-resistant alfalfa into silage corn (Zea mays). Studies were conducted in 2012 and 2013 at sites near Cache Junction and Cornish, Utah to determine the effect of tillage type and timing [fall conventional till (FCT), spring conventional till (SCT), fall strip-till (FST), spring strip-till (SST), and no-till (NT)], 2,4-D plus dicamba herbicide timing (fall, spring, in-crop, and a control), and N rate (0, 56, 112, and 224 kg N ha-1) on soil penetration resistance (PR), alfalfa re-growth, and corn emergence rate index (ERI), silage yield, quality, and economic return. The fall, spring, and in-crop herbicide timings across all tillage treatments reduced alfalfa stem count and biomass by at least 95% and 98%, respectively. Tillage reduced PR compared to NT to or near the depth of tillage. The ERI was significantly higher under FCT, SCT, and SST and when herbicides were applied in fall or spring. Silage yield, quality, and economic return were the highest when spring herbicide timing was used with all tillage types and timings and the fall herbicide timing under conventional tillage. Increasing N rates increased crude protein, milk ha-1, and dry matter yield. However, optimal yield and quality can be obtained with no additional N fertilizer. First-year silage corn yield, quality, and economic return can be optimized under fall or spring conventional till, strip-till, and no-till at the spring herbicide timing along with the fall herbicide timing for conventional tillage with no additional N fertilizer.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-3306 |
| Date | 01 May 2014 |
| Creators | Clark, Jason Daniel |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact Andrew Wesolek (andrew.wesolek@usu.edu). |
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