Soil Texture and Compaction

Soil texture may impose physical restrictions on the ability of fauna to graze on microbes; therefore, texture may play a role in faunal-induced mineralization of microbial carbon and nitrogen (van Veen and Kuikman, 1990). Carbon and nitrogen mineralization is generally faster in coarse than in fine-textured soils. In clay soils, organic material is protected physically from decomposers by its location in small pores. In sandy soils, organic matter is protected by its association with clay particles (Hassink et al., 1993a). Nematodes and microarthropods are often less abundant in heavy clay soil than in sandy or peat soil (van de Bund, 1970; Zirakparvar et al., 1980; Verma and Singh, 1989). Euedaphic species such as collembolans in the Onychiuridae and mesostigmatid mite Rhodacarus roseus are especially rare in clay soil (Didden, 1987).

Mesofauna are affected adversely by soil compaction (Aritajat et al., 1977a,b). Wheel-induced compaction reduces soil porosity, which is accompanied by a decrease in microbial biomass carbon and the density of Collembola (Heisler and Kaiser, 1995). Collembolans avoid narrow pores to protect their waxy surface from damage (Choudhuri, 1961). Wheel traffic decreased the density of collembolans and predatory mites by 30 and 60%, respectively, compared with noncompacted soil. The number of species was also reduced by compaction (Heisler, 1994).

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