Tillage systems threaten or promote soil biodiversity

Tillag is one of the most common soil management practices in agroecosystems worldwide. Conventional mouldboard ploughing is motivated by the efficient incorporation of crop residues, seed bed preparation and weed management. Ploughing induces many physical, chemical and biological changes in soil, with some well known negative effects. Reduced soil quality due to the loss of carbon and other nutrients, together with negative effects on soil structure, challenges the use of intensive and frequent ploughing as the ideal tillage regime. Ploughing also changes the composition of soil communities, and can lower both abundances and diversity of beneficial soil organisms. These include microbes and soil animals as: (i) chemical engineers in decomposing soil organic matter and recycling of carbon and other nutrients; (ii) biological regulators in controlling other soil organisms; and (iii) ecosystem engineers in forming and maintaining favourable soil structure. Their important contribution to ecosystem service provision in agricultural soils demands our understanding of the impacts of tillage on soil biodiversity. Reduced- and no-tillage systems, in conjunction with the retainment of crop residues as well as the application of diversified crop rotations, are known to promote soil biodiversity. There is a need to implement and further develop alternatives to conventional ploughing, as well as employ and preserve soil biodiversity, in order to improve the sustainability of agriculture. This chapter discusses major effects of soil tillage on soil organisms within a functional framework, in order to provide perspectives for their maintanance and enhancement in field management.