Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/3/2000
Publication Date: N/A
Technical Abstract: Earthworms are rare in dryland cropping systems of the Pacific Northwest. Possible reasons are the dry soil conditions during summer and intensive tillage common to the region. To test the effect of tillage, earthworm populations were measured in a tillage intensity experiment started in 1967 under a winter wheat/pea rotation. High intensity tillage, which involved moldboard plow, chisel plow, or disking every fall, produced the lowest earthworm populations at 1.7 to 3.4 Aporrectodea trapezoidez per square m. A delay in plowing winter wheat stubble until spring raised population to 5.6 per square m. Reducing tillage to 2.5 cm depth produced 25 earthworms per square m. It appears that modest earthworm populations are possible in this dryland region only under minimal or no tillage.