Location: Coastal Plain Soil, Water and Plant Conservation Research
Title: Benefits of brassica carinata as a double crop for cotton rotationsAuthor
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 12/1/2022 Publication Date: 1/15/2023 Citation: Billman, E.D., Campbell, B.T. 2023. Benefits of brassica carinata as a double crop for cotton rotations. Meeting Abstract. Interpretive Summary: . Technical Abstract: Cotton (Gossypium hirsutum L.) production in the southeastern United States typically uses cereal grass species as cover crops in rotations. Double cropping (harvesting of two crops in one season) is impractical with these species due to the spring planting of cotton. Cereal grass species also pose risks to subsequent cotton production by altering carbon-to-nitrogen ratios, creating excessive crop residue, and depleting soil nutrients via crop removal. Carinata (Brassica carinata A. Braun), a new bioenergy crop used for jet fuel production, may offer viable double cropping potential as well as physiological and agronomic benefits to a subsequent cotton crop. This study sought to compare the effects of growing a carinata double crop compared to a typical winter wheat (Triticum aestivum L.) or fallow system with no cover crop on cotton morphology, lint yield, and fiber quality over two growing seasons (2020 and 2021). Each year, cover crops were established in early November near Florence, SC with 73 × 18-m strips of carinata, wheat, and fallow. Cover crops were maintained until spring each year with carinata and wheat harvest occurring in late May, while the fallow area was burned down with glyphosate. All cover crop areas were then strip tilled, followed by cotton planting (DP 1646). Prior to fall harvest, border alleys were cut between cotton plots to create four replicates within each section of the preceding cover crop (carinata, wheat, or fallow), with plots being 18 × 18-m (12 plots total). The middle two rows of each plot were harvested for lint yield, while fiber quality samples were collected from random bolls outside the harvested rows. Additionally, whole plant samples were randomly collected for at-harvest plant mapping from a 1-m strip of row within each plot. All data was analyzed as a complete block study using SAS 9.4 to conduct analysis of variance and mean separation. Results indicated that seed cotton and lint yields following a carinata cover crop (2182 kg ha-1; 916 kg ha-1) were greater (P < 0.05) than cotton following winter wheat (1703 kg ha-1; 698 kg ha-1), and that cotton following winter wheat had lower (P < 0.05) lint yields than when following a fallow system (864 kg ha-1). Small effects were observed on fiber upper half mean length, strength, and elongation, but these were not enough to affect fiber classification or value. Notable differences were observed with at-harvest plant mapping, with cotton grown after carinata being taller (112-cm), as well as having more total bolls (17.2) and position 1 (9.5) and 2 (3.6) bolls (P < 0.01) compared to cotton after winter wheat. These effects were attributed to the potentially greater amount of K and Ca present in the preceding carinata cover crop, as well as the potentially greater soil K removal by the wheat cover crop, as both nutrients are critical to boll set, fill, and retention. We concluded that carinata is suitable to rotate with cotton in the Southeast US, provided careful harvest timing in spring does not delay cotton planting. |
