SPATIAL DISTRIBUTION OF THE FAUNA OF THE SOIL ON THE LONG-TERM SYSTEM OF DIRECT SOWING

Abstract

The soil is a complex system constituted of living beings, minerals and organic particles, whose components define their physical, chemical and biological properties. The fauna of the soil has an important role in the soil and its diversity can reflect and interfere with the functioning of the soil. The population of these organisms can be influenced by management practices, fertilizing, liming, porosity, and others. Such changes may reduce the composition and the distribution of soil fauna community. Thus, the aim of this work was to determine the spatial variability of the soil fauna in the consolidated direct sowing. The experimental area is located in the CEC (Experimental center of the central Agronomy Institute) in Campinas, Sao Paulo. The sampling was carried out in Eutroferric Red Latosol, with direct sowing. In the area were sampled 302 points distributed in a 3.2-hectare area on a regular grid of 10m x 10m. The fauna was sampled by pitfall traps method and the traps remained in the area for a seven days period. The data were analyzed through descriptive statistics for determining the main statistical moments (average, variance, the coefficient of variation, standard deviation, skewness, and kurtosis). Geostatistics tools were used to determine the spatial variability of the attributes in studies using the experimental semivariogram. In the biodiversity analysis, was calculated Shannon index for each sample, the richness and the number of individuals. The geostatistical demonstrated to be a great tool for the mapping of spatial variability of the epigeal group fauna of the soil. The Family Formicidae has demonstrated to be the most abundant and dominant group in the study area. The parameters of descriptive statistics have demonstrated that all the attributes in the study presented lognormal frequency distribution for the epigeal group fauna of the soil. The exponential model was that which best adjusted to the data in the study, both for the epigeal group fauna of the soil groups (Acari, Araneae, Coleoptera, Formicidae and Larva of Coleoptera), as for the biological diversity index (Shannon Index and Pielou Index). The sampling scheme (10,00m x 10,00m) was not enough to detect the spatial variability for all groups of epigeal group fauna of the soil found in this study.