Influence of mulch and soil compaction on earthworm cast properties

The effects of different mulch materials applied to compacted and uncompact ed soil on the quantity and the quality of deposited earthworm casts were i nvestigated. Biochemical properties and water stability of soil aggregates were compared with the corresponding properties of worm casts. This short-t ime experiment was conducted in the laboratory, simulating field conditions of mulch management in temperate agricultural systems. In microcosms Lumbr icus terrestris and Octolasion cyaneum were inoculated separately. Barley, lupin, maize, or sugar-beet as straw or leaves were applied as mulch in amo unts comparable to those usually found in the field. The soil was compacted artificially to a bulk density of 1.0 or 1.5 Mg m(-3) In general, plant ma terial and to a lesser extent soil compaction influenced the dynamic proces ses in the soil affecting microbial activity and water stable aggregation. Higher values of phosphatase activity was measured in compacted soil, while the corresponding enzyme activities in the casts were less affected by com paction. The worm species and the nutritional quality of the food source we re factors strongly influencing water stable aggregation. Mulch as well as soil compaction had consequences for the burrowing activity of the worms, w hich resulted in different rates of cast production depending on the specie s. (C) 2000 Elsevier Science B.V. All rights reserved.