Seasonal variations in infiltration rate under no-till and conventional (disk) tillage systems as affected by Lumbricus terrestris activity

Lumbricus terrestris activity can improve water flow into soils, but the effects of L. terrestris (nightcrawlers) on infiltration and runoff rates throughout the growing season have not been quantified. Our objective was to quantify and describe the effects of L. terrestris on infiltration rates under an established no-till and a disk tillage system on a silt loam Alfisol (fine-loamy, mixed, mesic Aquollic Hapludalf) in west central Indiana. Under each tillage practice there were areas within the field that had L. terrestris activity and other areas that had no activity, as indicated by the presence or absence, respectively, of middens. Infiltration was measured using a portable sprinkling infiltrometer which delivered 7 cm of water h−1 to a 1.4 m2 area. Infiltration was measured five times during the growing season, for the disk tillage treatment: (1) before any spring field work began; (2) immediately after tillage but before planting; (3) immediately after planting; (4) 3 weeks after planting; and (5) after harvest. For no-till treatments, the measurement times were the same as times 1, 3, 4, and 5 of the tilled site. Results showed that in early spring before any tillage was performed, the tilled treatment without middens had the highest infiltration rate and the tilled treatment with middens had the lowest. Immediately after planting and 3 weeks after planting, no-till with middens had the highest infiltration rates, but disk tillage treatments had the lowest infiltration rates. Measurements after harvest showed that no-till with middens again had the highest infiltration rates. The presence of L. terrestris, as indicated by the presence of middens, appears to have increased infiltration rates in a no-till system on this soil. In the disk system, however, the activity of L. terrestris and the presence of their middens apparently was not persistent enough to affect infiltration rates, and the amount of surface residue cover may be a more important factor in this system.