Abstract. Cover crops have been recognized as a vital part of conservation agriculture, but they need to be managed appropriately to avoid planting problems related to the large amounts of biomass. Typically, cover crops are rolled in the same direction as the travel direction of the planter, but producers have been inquiring if other rolling directions are also effective. To answer this question, replicated field experiments (split-plot design) were conducted at two locations in Alabama during three growing seasons to evaluate different rolling directions of a cereal rye cover crop, i.e., non-rolled (standing rye), 0° (cotton planting direction), 180° (opposite of planting direction), 15° (offset from 0°), and 195° (15° offset from 180°), using a roller/crimper. A no-till cotton planter with different row cleaners, i.e., a commercially available row cleaner (Dawn with coulter), a residue pusher with and without a coulter, and no row cleaner (control), was used to determine the effects of rolling direction and row cleaners on cotton population, emergence rate, and yield. The rye cover crop was terminated with a roller/crimper and glyphosate. Among growing seasons, significant differences existed in rye production, cotton population, emergence rate index (ERI), seed cotton yield, amount of residue accumulated on the planter, and the time required to remove residue from the planter. For the rolling direction treatments, higher cotton population was found for 0° and non-rolled rye, and the lowest population was found with 195°. The ERI was higher for 0° and non-rolled rye, and the lowest ERI was observed for 195°. For the row cleaner treatments, the cotton population and ERI were both higher for Dawn with coulter and pusher with coulter. Across three growing seasons, cotton yield was not affected by rolling direction but was affected by row cleaner. Significantly higher cotton yield was associated with Dawn with coulter and pusher with or without coulter, compared to lower yield for no row cleaner. The important findings were that residue accumulation was not problematic when the cover crop was rolled. When the cover crop was not rolled, the pusher accumulated more residue than Dawn with coulter; however, the time required to remove the residue was more than 3 times higher for Dawn with coulter as compared to the pusher. The data indicated that, across all growing seasons and locations, rolling direction and row cleaner affected the cotton population, ERI, residue accumulation on the planter, and the time required to remove residue. In contrast, rolling direction did not affect seed cotton yield, but row cleaner had an effect on seed cotton yield. Based on the results, the best combination of rolling direction and row cleaner was 15° offset to the cotton planting direction and Dawn with coulter, which resulted in higher cotton population, ERI, and seed cotton yield without residue accumulation on the row cleaner. However, the 0° and 180° Dawn with coulter and 15° pusher with coulter combinations were also effective in producing relatively higher cotton population, ERI, and seed cotton yield. Keywords: Conservation system, Cotton yield, Emergence, Plant population, Residue pusher, Roller/crimper, Rolling direction, Row cleaner, Rye cover crop.
Systemic Colonization by Metarhizium robertsii Enhances Cover Crop Growth
