ROLE OF LUMBRICUS-TERRESTRIS (L) BURROWS ON QUALITY OF INFILTRATING WATER

Long-term watershed studies at the North Appalachian Experimental Watershed, Coshocton, Ohio have shown that when com (Zea mays L.) is planted in soil covered by the residue of the previous crop (i.e. no-tillage management), surface runoff from summer storms is greatly reduced. In addition, the residue cover provides a favorable environment for various soil invertebrates, especially earthworms. During high-intensity rainstorms, some of the water that infiltrates in no-till com fields moves rapidly downward in burrows made by the earthworms Lumbricus terrestris L. Samplers were developed for collecting infiltrating rain water flowing in L. terrestris burrows at a depth of 45 cm below the soil surface. With annual surface applications of 175 kg N ha-1 as NH4NO3, concentrations of NO3-N in water flowing in individual burrows during growing season storms ranged up to 152 mg l-1. Concentrations of NO3-N tended to be lowest after prolonged wet soil conditions and highest after intermittent warm, dry periods. Distilled water poured directly into the surface openings of L. terrestris burrows and immediately collected as it drained into samplers, contained up to 40 mg of NO3-N l-1, a value greater than that measured in many of the samples resulting from natural min storms. Water and herbicide mixtures poured through L. terrestris burrows showed that the linings of the burrow, or drilosphere, may contribute nitrogen to the infiltrating water while greatly reducing the concentrations of atrazine and alachlor.