Cropping Systems for Perennial Ryegrass Seed Production: I. Minimum Tillage Establishment of Rotation Crops in Stubble Without Burning

Viability of alternative crops in a monoculture grass seed cropping system will be enhanced if minimum tillage establishment through grass seed stubble is successful without burning. Our objective was to compare agronomic performances of red clover ( Trifolium pratense L.), white clover ( T. repens L.), meadowfoam ( Limnanthes alba L.), and pea ( Pisum sativum L.) when drill‐seeded in the stubble of a third‐year perennial ryegrass ( Lolium perenne L.) seed crop, with and without burning stubble. Four field experiments were conducted during a 6‐yr period on a Woodburn silt‐loam (fine‐silty, mixed, mesic Aquultic Argixerolls) soil in western Oregon. Ryegrass stubble was either propane‐burned or was not burned before drill‐seeding the rotational crops. In one experiment, a rotary strip‐till drill was also compared with a no‐till drill for establishing white clover in perennial ryegrass stubble. Burning the stubble enhanced spring growth of red clover; however, forage and seed yields in the first crop year were 47 and 66% higher, respectively, for the nonburned than the burned treatments. There were no differences among treatments for forage and seed yields of red clover in the second crop year. Treatments did not affect dry matter or seed production of white clover and spring pea. Meadowfoam forage and seed yields were 26 and 24% lower, respectively, for the nonburned than the burned treatments. We concluded that burning stubble before seeding may be advantageous for winter annual seed crops that mature during the spring or early summer months. However, burning stubble is not beneficial, or may be disadvantageous, for crops that mature during the late summer in areas such as Oregon with a Mediterranean climate. The no‐till drill was superior to the strip‐till drill for establishing white clover in perennial ryegrass stubble regardless of stubble management method.