Observations on Earthworm Channels and Infiltration on Tilled and Untilled Loess Soil

The number of earthworm channels ranging from 2 to 11 mm in diameter were counted to 80 cm depth in tilled and untilled grey-brown podzolic soil derived from loess. Number and percentage volume of earthworm channels in the Ap horizon approximately doubled during 4 years of no-tillage practice as compared to the tilled plot. Almost all the channels of the Ap horizon in the untilled plot had ports at the soil surface and were capable of taking in tension-free irrigation water and transmitting free water to a maximum depth of 180 cm, where the channels end at the transition to unweathered loess. The channels in the Ap horizon of the tilled plot were not effective in water transmission. The same is true for a large number of channels in the subsoil of tilled and untilled plots, which could not contribute to water infiltration because they were not connected with the soil surface. The maximum infiltrability of conducting channels in the untilled soil was computed as more than 1 mm (1 liter per m2) per minute, although the volume of these channels amounted to only 0.2 vol. %.