Effect of Seeding Rate and Planting Arrangement on Rye Cover Crop and Weed Growth

Weed growth in winter cover crops in warm climates may contribute to weed management costs in subsequent crops. A 2‐yr experiment was conducted on an organic vegetable farm in Salinas, California, to determine the impact of seeding rate and planting arrangement on rye ( Secale cereale L. ‘Merced’) cover crop growth and weed suppression. Each year, rye was planted in October at three rates (90, 180, and 270 kg ha −1 ) and two planting arrangements (one‐way versus grid pattern). Averaged across years, rye population densities were 322, 572, and 857 plants m −2 at the 90, 180, and 270 kg ha −1 seeding rates, respectively. Early season rye ground cover increased with seeding rate and was higher in the grid than one‐way arrangement in Year 1; however, rye ground cover was not affected by rate and was higher in the one‐way arrangement in Year 2. Aboveground dry matter (DM) of rye increased with seeding rate at the first two harvests but not at the final one. Planting arrangement did not affect rye aboveground DM in Year 1, but rye DM was higher in the grid pattern at the first and final harvests in Year 2. Weed emergence was not affected by seeding rate or planting arrangement. Weed biomass decreased with increased seeding rate and was also lower in the grid than in the one‐way arrangement in Year 2. A grid planting pattern provided no consistent benefit but planting rye at higher seeding rates maximizes early season rye DM production and minimizes weed growth.