Plant decomposition is dependant on the activity of the soil biota and its interactions with climate, soil properties, and plant residue inputs. This work assessed the roles of different groups of the soil biota on litter decomposition, and the way they are modulated by soil use. Litterbags of different mesh sizes for the selective exclusion of soil fauna by size (macro, meso, and microfauna) were filled with standardized dried leaves and placed on the same soil under different use intensities: naturalized grasslands, recent agriculture, and intensive agriculture fields. During five months, litterbags of each mesh size were collected once a month per system with five replicates. The remaining mass was measured and decomposition rates calculated. Differences were found for the different biota groups, and they were dependant on soil use. Within systems, the results show that in the naturalized grasslands, the macrofauna had the highest contribution to decomposition. In the recent agricultural system it was the combined activity of the macro- and mesofauna, and in the intensive agricultural use it was the mesofauna activity. These results underscore the relative importance and activity of the different groups of the edaphic biota and the effects of different soil uses on soil biota activity.

1The processes involved in the flows of matter and energy of terrestrial ecosystems depends 2 heavily on soil biological activity, the current conventional agricultural managements could alter 3 the biological mechanisms involved in decomposition and nutrient cycling in agroecosystems. 4The aim of this study was to compare the activity levels and soil microbial biomass between 5 different agricultural pampean soil uses and its relationship to carbon mineralization. 25 years of 6 agricultural use were compared with 25 years of ecological reserve naturalized where each 7 agroecosystem soil were collected at 61 -125 -183 -236 -302 -368 -431 -488 days for 8 measuring their moisture, organic matter, enzymatic activity, microbial biomass carbon, soil 9 respiration, metabolic quotient, microbial quotient and carbon mineralization rate. The distance 10 between agroecosystems is less than 800 m, thus assuming the same soil and climatic conditions. 11The data were evaluated by Friedman test finding significant differences in moisture, organic 12 matter, enzymatic activity, soil respiration y microbial quotient (p< 0.01). Difference was also 13 found in the microbial mineralization rate of carbon (p< 0.1). 14 KEY WORDS 15Microbiological activity; carbon mineralization; soil use. 16PeerJ PrePrints | https://doi.org/10.7287/peerj.preprints.1608v1 | CC-BY 4.0 Open Access |

Edaphic fauna play a crucial role in soil processes such as organic matter incorporation and cycling, nutrient content, soil structure, and stability. Collembolans in particular, play a very significant role in nutrient cycling and soil structure. The structure and functioning of the soil fauna can in turn be affected by soil use, leading to changes in soil characteristics and its sustainability. Therefore, the responses of soil fauna to different soil management practices, can be used as ecological indicators. Three different soil uses were researched: agricultural fields (AG) with 50 years of continuous farming, pastures entering the agricultural cycle (CG), and naturalized grasslands (NG). For each soil use, three fields were selected. Each sampling consisted of three soil samples per replicate. Collembolans were extracted from the samples and identified to family level. Five families were found: Hypogastruridae, Onychiuridae, Isotomidae, Entomobryidae, and Katiannidae. Soils were also characterized by means of physical and chemical analyses. The index of degree of change of diversity, was calculated. The results show that the biological index of degree of change can detect soil use effects on the collembolan community. Somewhat surprisingly the index showed that the diversity of collembolans is higher in the high anthropic impact site AG, followed by CG and being lower in lower impact sites, NG. The results also show that collembolan families respond differently to soil use. The families Hypogastruridae, Onychiuridae, and Isotomidae presented differences between systems. Therefore collembolan community structure can be a useful tool to assess agricultural practices´ impacts on soil.

Edaphic fauna play a crucial role in soil processes such as organic matter incorporation and cycling, nutrient content, soil structure, and stability. Collembolans in particular, play a very significant role in nutrient cycling and soil structure. The structure and functioning of the soil fauna can in turn be affected by soil use, leading to changes in soil characteristics and its sustainability. Therefore, the responses of soil fauna to different soil management practices, can be used as ecological indicators. Three different soil uses were researched: agricultural fields (AG) with 50 years of continuous farming, pastures entering the agricultural cycle (CG), and naturalized grasslands (NG). For each soil use, three fields were selected. Each sampling consisted of three soil samples per replicate. Collembolans were extracted from the samples and identified to family level. Five families were found: Hypogastruridae, Onychiuridae, Isotomidae, Entomobryidae, and Katiannidae. Soils were also characterized by means of physical and chemical analyses. The index of degree of change of diversity, was calculated. The results show that the biological index of degree of change can detect soil use effects on the collembolan community. Somewhat surprisingly the index showed that the diversity of collembolans is higher in the high anthropic impact site AG, followed by CG and being lower in lower impact sites, NG. The results also show that collembolan families respond differently to soil use. The families Hypogastruridae, Onychiuridae, and Isotomidae presented differences between systems. Therefore collembolan community structure can be a useful tool to assess agricultural practices´ impacts on soil.