Comparison of Mechanical and Chemical Winter Cereal Cover Crop Termination Systems and Cotton Yield In Conservation Agriculture
2009
Price, Andrew J. | Arriaga, Francisco J. | Raper, Randy L. | Balkcom, Kipling S. | Komecki, Ted S. | Reeves, D Wayne
An integral component of conservation agriculture systems in cotton (Gossypium hirsutum L.) is the use of a high-residue winter cover crop; however, terminating cover crops is an additional expense and planting into high-residue can be a challenge. An experiment was conducted using black oat (Avena strigosa Schreb.), rye (Secale cereale L.), and wheat (Triticum aestivum L.) cover crops established in early November at three locations. In mid-April each year all winter cover crops were flattened with a straight-blade mechanical roller-crimper alone or followed by three rates of glyphosate (0.84, 0.42, 0.21 kg ae/ha). Additionally, glyphosate alone at each rate and a non-treated check were included to complete the factorial treatment arrangement. Cotton was then planted 3 weeks after treatments were administered following in-row sub-soiling at E.V. Smith and direct seeding at Tennessee Valley and Robertsdale. Results showed that rolling followed by reduced glyphosate rates as low as 0.42 kg ae/ha can effectively and reliably terminate mature cereal winter cover crops; thus maintaining cotton population and protecting growth. Additionally, reduced glyphosate rates applied as low as 0.84 kg ae/ha alone can effectively terminate immature cereal covers while conserving soil moisture. Rolling mature winter cereal cover crops will likely conserve more soil moisture compared to standing covers; however, rolling immature cereal cover crops provides no benefit. In 2005 at E.V. Smith and at Tennessee Valley in 2006, increasing glyphosate rate increased cotton yield likely due to less mature cereal covers at time of treatment application. However, the inclusion of glyphosate did not increase cotton yield for any other comparison.
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