Benefits and risks of increasing cover crop plant family and species diversity in cotton

Authors: Billman, Eric

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 12/2/2025
Publication Date: 1/9/2026
Citation: Billman, E.D. 2026. Benefits and risks of increasing cover crop plant family and species diversity in cotton. Proceedings of National Cotton Council Beltwide Cotton Conference, Januray 7-9, 2026, San Antonio, Texas.

Interpretive Summary: Technical Abstract only

Technical Abstract: Implementation of cover crops in cotton production has several purported benefits, with nutrient credits and soil health benefits being consistently reported. However, the effects of increased cover crop plant family and species diversity have not been examined in cotton production. This study compared cotton morphology, physiology, yield, and soil fertility when following monocultures and mixtures of cover crop species within the three most common plant families: 1.) grass, using cereal rye (Secale cereale L.), 2.) legume, using crimson clover (Trifolium incarnatum L.), and 3.) forb, using carinata (Brassica carinata A. Braun). In each of two consecutive years, cover crops were planted in fall, terminated with herbicide and roller crimped in spring, then interseeded with cotton. All plots were fertilized uniformly with 90-kg N ha-1 regardless of cover crop treatment. Cotton moisture stress was reduced by mixing rye with carinata but increased by growing crimson clover with rye. Mixtures of crimson clover and carinata resulted in excess nitrate-N availability during flowering and greater organic matter deposition, while carinata and cereal rye increased P and Ca availability. Lint yields were greatest where cereal rye and carinata were grown as monocultures or mixtures, while crimson clover reduced lint yields. Lastly, increasing species diversity in mixtures increased the presence of monopodial branches and bolls. These findings indicated that growing cereal rye or carinata as monocultures or mixtures would provide greater lint yields, increase soil fertility, and minimize excessive vegetative growth in cotton due to excessive fertilization. Increased N availability provided by crimson clover and carinata further indicated that conventional N fertilization could be substantially reduced to provide cost savings to producers while maintaining or improving lint yield potential.