Cover cropping history affects cotton boll distribution, lint yields, and fiber quality

Authors: Billman, Eric; Campbell, Benjamin - Todd

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2023
Publication Date: 2/7/2023
Citation: Billman, E.D., Campbell, B.T. 2023. Cover cropping history affects cotton boll distribution, lint yields, and fiber quality. Crop Science. 63(3):1209-1220. https://doi.org/10.1002/csc2.20931.
DOI: https://doi.org/10.1002/csc2.20931

Interpretive Summary: Cover cropping in the southeastern United States has seen little innovation in the last 20 years. Either cereal grasses such as winter wheat or cereal rye, or legumes such as crimson clover or hairy vetch are commonly recommended for cotton production in the region, despite mounting evidence that these species either deplete soil nutrient reserves or provide inadequate weed suppression. The oilseed crop Brassica carinata, or simply carinata, may provide a dual use cover crop for the jet fuel industry that also improves soil organic matter, and returns more macronutrients to the soil. A 2-year study compared the effects to a cotton crop in the Southeast when growing a carinata cover crop vs traditional winter wheat and fallow with no cover crop. Cotton yield was consistently greater when growing carinata as a cover crop, which was attributed to greater total number of bolls on the cotton plants grown after carinata. Additionally, cotton grown after carinata retained almost twice as many bolls per plant compared to a wheat or fallow system, which was likely due to increased potassium and calcium that are returned to the soil from carinata crop residue. These findings indicate that carinata can serve as a beneficial dual-use cover crop for southeastern cotton production systems.

Technical Abstract: There has been limited introduction of new cover crop species into cotton (Gossypium hirsutum L.) production within the last 30 years. Mounting evidence shows that traditional cover cropping species may be detrimental to cotton production, either by depleting soil fertility with crop removal, immobilizing minerals from high carbon residue, or excessive quantity of residue remaining at planting. The objective of this study was to determine the effects of growing a novel cover crop species, carinata (Brassica carinata A. Braun), as a winter annual cover crop for cotton rotation in the southeastern Coastal Plain. Over a two-year period, carinata, winter wheat (Triticum aestivum L.), and fallow covers were maintained over winter months, then rotated into cotton. Each year, seedcotton and lint yields were collected, along with subsamples for ginning and subsequent fiber quality analyses. Additionally, end-of-season plant mapping was conducted on plants from 1-m of row per plot to determine cover crop effects on boll formation, retention, and distribution, as well as canopy architecture. Results indicated that seedcotton and lint yield of cotton following carinata was greater than cotton following winter wheat, and lint yields of cotton following wheat were lower than cotton after fallow. Fiber quality was largely unaffected by preceding cover crop. End-of-season plant mapping indicated that cotton grown after carinata had more position 2 bolls, which correlated to greater lint yields. These results indicate that carinata can potentially serve as a new, more effective cover crop than winter wheat for cotton rotations in Coastal Plain soils.