Earthworm populations and species distributions under no-till and conventional tillage in Indiana and Illinois

Abstract

Earthworms often play an important role in maintaining or improving soil physical conditions, and earthworm populations often increase under reduced tillage systems. The objective of our study was to determine earthworm populations and species distributions under long-term no-till vs conventional tillage on a variety of soil types in the states of Indiana and Illinois, U.S.A. Fourteen paired sites were located on farmers' fields. Each paired site consisted of a no-till and conventional tillage field on the same soil type, located as close together as possible. Fields were in corn ( Zea mays L.)-soybean ( Glycine max) rotation, and earthworm counts were made in the spring following a soybean crop. Populations of shallow-dwelling earthworms (endogees) ranged from 2 to 343 earthworms per m −2. Of the 14 paired sites, eight sites had higher earthworm populations in no-till than conventional, four sites had roughly equal populations in both systems, and two sites had slightly lower populations in no-till than conventional. At most sites, shallow-dwelling species were dominated by Apporectodea tuberculata and A. trapezoides. Some of the sites also had significant populations of Lumbricus rubellus. The presence or absence of significant L. terrestris populations was noted by observing middens. Nine no-till and three conventional sites showed significant activity of L. terrestris. Implications for tillage management and the need for additional applied research are discussed.