TY - JOUR T1 - Water infiltration rates following reintroduction of <em>Lumbricus terrestris</em> into no-till fields JF - Journal of Soil and Water Conservation SP - 82 LP - 88 VL - 57 IS - 2 AU - G. L. Willoughby AU - E. J. Kladivko Y1 - 2002/03/01 UR - http://www.jswconline.org/content/57/2/82.abstract N2 - The deep-burrowing earthworm species Lumbricus terrestris (nightcrawler) can have significant impacts on water infiltration rates in soils. Many farmers using no-till practices want to encourage higher nightcrawler populations in their fields, and a few have questioned whether it would be useful to distribute collected or purchased nightcrawlers throughout their fields. In this study, adult L. terrestris were reintroduced into some no-till fields to determine their survival, population growth, and subsequent impact on infiltration rates. Three no-till fields devoid of L terrestris, as evidenced by the absence of surface middens had 12 quadrats, 2m × 2m in size, established in spring 1994. Six quadrats were seeded at a rate of 20 L. terrestris/m2, and six were left as controls. Over two years, the number of middens varied from o to 6.5 L. terrestris/m2 in each seeded quadrat, with none in the control plots. We determined infiltration using a sprinkling infiltrometer that applied 7.5 cm of water per hour. In seeded plots, final infiltration rates ranged from 1.20 to 0.33 mm/min (average 0.80) across both years, and in control plots they ranged from 1.17 to 0.38 mm/min (average 0.71). Presence of L. terrestris significantly increased infiltration rates in 1995; however, in 1996 there were no significant increases in infiltration rates, probably because of a large decrease in population numbers from 1995 to 1996. Six larger (4m × 4m) quadrats were also seeded with 20 L. terrestris/m2, and another six were left as controls. Within these quadrats, a comparison of sprinkler vs. ponded infiltration methods was performed. There were no significant differences in infiltration detected between seeded and control quadrats at the end of 55 or go minutes, but there was a trend for greater infiltration in the seeded quadrats. There were no significant differences between infiltration methods when data were analyzed at the end of 55 minutes (the duration of the sprinkling infiltrometer procedure). Higher populations of L. terrestris may be needed before significant differences in infiltration rates or methods are detected. Results of the first two years indicate that nightcrawlers may survive and become reestablished in many no-till fields, but the rate of population growth and soil property improvements may be slow enough to discourage large-scale seeding efforts by farmers. ER -