Effect of Soybean Maturity, Crimson Clover Seeding Method, and Seeding Rate on Clover Biomass and Nitrogen Content

CORE IDEAS: Crimson clover seeding following the last cultivation of soybeans in July into MG3 to MG5 soybeans did not result in any substantial crimson clover growth in both years. After harvest seeding into MG3 and MG4 soybean and aerial seeding into MG4 and MG5, soybean produced substantial clover N content ranging from 76 to 107 kg ha⁻¹. After harvest seeding behind MG5 soybeans reduced clover N content because late cover crop establishment restricted biomass production. Seeding rate had no effect on clover biomass, clover N content, or corn yield for both drilled and aerially‐seeded crimson clover. Timely crimson clover (Trifolium incarnatum L.) establishment is a management challenge for producers in the southeastern United States. Aerial seeding methods and the use of early maturing soybeans may allow for earlier crimson clover establishment and potentially increase nitrogen contributions to the following crop. A soybean (Glycine max L.)–crimson clover–corn (Zea mays L.) rotation experiment was conducted in Goldsboro, NC from 2006 to 2008. Three crimson clover seeding methods were evaluated: aerial seeding after last soybean cultivation, aerial application before soybean leaf drop, and after‐harvest drill seeding. Each seeding method was evaluated in three soybean maturity groups (MG; 3, 4, 5) and contained three crimson clover seeding rates (22, 39, 56 kg ha⁻¹). Clover biomass accumulation, clover N content, and corn yield were determined. Crimson clover seeding following the last cultivation of soybeans into MG3, MG4, and MG5 did not result in any substantial crimson clover growth. After harvest seeding into MG3 and MG4 soybean residue and aerial seeding prior to soybean leaf drop into MG4 and MG5 soybean produced substantial clover N content ranging from 76 to 107 kg ha⁻¹. After‐harvest seeding behind MG5 soybeans reduced clover N content likely because late cover crop establishment restricted biomass production. Seeding rate had no effect on clover biomass, clover N content, or corn yield. An independent crimson clover aerial seeding rate experiment conducted from 2006 to 2008 in Goldsboro, NC also confirmed no effect of crimson clover seeding rate on clover biomass or N content.