Skip to main content
ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #218109
Title: Effect of Seeding Rate and Planting Arrangement on Rye Cover Crop and Weed Growth

Author
item BOYD, NATHAN - NOVA SCOTIA AGRI. COLLEGE
item Brennan, Eric
item SMITH, R - UC COOP. EXTENSION
item TOKOTA, RON - TANIMURA & ANTLE

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2009
Publication Date: 7/1/2009
Citation: Boyd, N.S., Brennan, E.B., Smith, R., Tokota, R. 2009. Effect of Seeding Rate and Planting Arrangement on Rye Cover Crop and Weed Growth. Agronomy Journal 101:47-51.

Interpretive Summary: Winter cover crops are important in organic vegetable rotations and can suppress weeds, reduce nitrate leaching and add soil organic matter. Weeds that grow in winter cover crops in warm climates may contribute to weed management costs in subsequent vegetable crops that are grown during warmer periods because many weed species occur year round. An experiment was conducted on an organic vegetable farm in Salinas, California, to determine how the cereal rye seeding rate and planting pattern affected cover crops growth and weed suppression over two winters. ‘Merced’ rye was planted with a grain drill in October at three rates (90, 180, and 270 kg ha-1) and two planting patterns (one-way versus grid pattern) and was terminated by flail mowing and disking 4 to 5 months later. Cover crop and weed growth were measured in the beginning, middle, and end of each cover cropping period. Seeding rate increased early season ground cover by rye in year 1 but not in year 2. Above ground dry matter of rye increased with seeding rate in the beginning and middle of the season but not at the season end. Planting arrangement had an inconsistent affect on rye biomass production and weed suppression. Increasing rye seeding rate consistently improved weed suppression. There were no consistent benefits to planting in the grid pattern, but planting rye cover crops at higher seeding rates would be worthwhile to maximize early season cover crop biomass production and to minimize weed growth. Planting in a grid pattern required two passes through the field that would likely double dust production, fuel use, planting time and labor needed to plant a cover crop.

Technical Abstract: Weed growth in winter cover crops in warm climates may contribute to weed management costs in subsequent crops. A two year 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. cv. Merced) cover crop growth and weed suppression. Each year, the cover crop was planted in October at three rates (90, 180, and 270 kg ha-1) and two planting arrangements (one-way versus grid pattern) and was terminated by flail mowing and disking 4 to 5 months later. Cover crop and weed growth were measured in the beginning (harvest 1), middle (harvest 2), and end (harvest 3) of each cover cropping period. Averaged across years, rye population densities were 324,574 and 866 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 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. Rye plants grew taller and produced fewer tillers as seeding rate increased. Above ground dry matter of rye increased with seeding rate at harvest 1 and 2 but not at harvest 3. Planting arrangement did not affect rye above ground dry matter in year 1, but rye dry matter was higher in the grid pattern at harvest 1 and 3 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 yare 2. There were no consistent benefits to planting in the grid pattern, but planting rye cover crops at higher seeding rates would be worthwhile to maximize early season cover crop biomass production and to minimize weed growth.