Comparison of Microbial Gene Diversity in Grassland Topsoil Depending on Soil Quality

Abstract

Soil has multiple functions, including the provision of habitat to organisms, and most biological activities occur in the surface soil. Due to the negative effects of soil erosion, efforts for soil conservation are being made, including the development of a reliable index that can help assess soil quality. In this study, the physical and chemical properties and biological genes from grassland topsoil were analyzed, in order to identify surface soil organism markers that could be used as a soil quality index. Six spots of grassland topsoil were analyzed, one high-quality and five low-quality, based on a web-based soil quality assessment module. Consequently, eukaryotes and prokaryotes with different soil quality ratios were compared and examined. The following bacteria and archaea have the potential to be used in soil quality assessment: circulation of materials including nitrogen, Nitrospira spp., Candidatus Nitrososphaera, and Candidatus Nitrosotalea; biological purification, Geobacter spp.; pathogens, Burkholderia spp., Paraburkholderia spp., Pseudomonas brassicacearum, and Rhizobacter spp.; antibiotic secretion, Candidatus Udaeobacter; and material degradation Steroidobacter spp. and Rhodanobacter spp. This study provides primary data for identifying biological markers for soil quality evaluation. In the future, a wider variety of data need to be accumulated to develop a highly reliable index related to soil quality.