Rye planting date impacts biomass production more than seeding rate and nitrogen fertilizer

Authors: Balkcom, Kipling; Read, Quentin; GAMBLE, AUDREY - Auburn University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2023
Publication Date: 7/31/2023
Citation: Balkcom, K.S., Read, Q.D., Gamble, A. 2023. Rye planting date impacts biomass production more than seeding rate and nitrogen fertilizer. Agronomy Journal. 115(5):2351–2368. https://doi.org/10.1002/agj2.21418.
DOI: https://doi.org/10.1002/agj2.21418

Interpretive Summary: Growers that plant cover crops outside optimal planting periods may alter cover crop management to improve biomass production by increasing seeding rates and/or applying greater N rates, but both factors increase production costs. However, limited research has been conducted to determine if enhanced cover crop biomass production is possible by increasing costly inputs during these non-optimal planting periods. In order to assist growers with these cover crop management decisions, ARS scientists in Auburn, AL, Raleigh, NC, and Auburn Univ. investigated how four planting dates (late October, early November, late November, and early December), two seeding rates (67 and 101 kg ha-1), and four N rates (0, 34, 67, and 101 kg N ha-1) affected rye performance in a peanut/cotton rotation over six growing seasons (2015-2020). Biomass production decreased as planting date was delayed across all N rates, while seeding rate had no effect. Despite a biomass response to N across planting dates, increasing N fertilizer for a late planted cereal cover crop did not produce additional biomass compared to an early planted cereal cover crop. Planting cover crops by early November was imperative to stimulate biomass production for this region. Increasing seeding rates and/or N applications was an unnecessary expense that could not overcome environmental constraints of late planting dates.

Technical Abstract: Management is critical to maximize cover crop benefits, while minimizing costs. However, cover crop performance and cost can vary without consistent management strategies. Therefore, we investigated how four planting dates (late October, early November, late November, and early December), two seeding rates (67 and 101 kg ha-1), and four N rates (0, 34, 67, and 101 kg N ha-1) affected rye (Secale cereale L.) (cv. ‘Wrens Abruzzi’) biomass production, N uptake, C:N ratio, US$ per 100 kg biomass, cash crop yields, and soil organic C (SOC) in a peanut (Arachis hypogaea L.)/cotton (Gossypium hirsutum L.) rotation over six growing seasons (2015-2020) in Headland, Alabama, USA. Biomass production averaged 2.7 times greater for late October planted rye compared to early December across all N rates. Nitrogen increased biomass production, but total biomass amounts decreased with later planting dates. Nitrogen uptake increased as N rate increased for each planting date. The C:N ratio was more sensitive to planting dates than N rates and decreased as planting was delayed. The US$ per 100 kg of biomass was similar across all N rates for early planting dates (late October and early November). No yield effect was observed for peanut or cotton, but SOC increased in the 0-5 cm depth when 101 kg N ha-1 was applied to the rye cover crop. Results highlight the importance of planting date compared to seeding and N rates to enhance cover crop performance and return on investment (ROI) for growers in the southeastern U.S.