Correlação entre enzimas microbianas no solo e comunidade de nematoides em sistemas de plantio direto orgânico

Abstract

The sustainability of organic agricultural systems is intrinsically linked to soil biological quality. This study aimed to relate the structure of free-living nematode communities with the activity of microbial enzymes (β-glucosidase, acid phosphatase, and arylsulfatase) in a no-till organic system under seven different crop rotations, seeking to identify integrated indicators of soil quality. Twenty composite soil samples (0-10 cm) were collected in an experimental area. Nematodes were quantified and identified, ecological indices (diversity, maturity, trophic ratios) were calculated, and the activity of the three enzymes was determined. Data were subjected to descriptive statistics, correlation analysis, geostatistics (kriging), principal component analysis (PCA), and clustering. Results revealed high spatial variability in nematode abundance, with dominance of bacterivore groups (56.5%) and a decreasing gradient of diversity and maturity among plots. Enzymatic activities showed independent spatial patterns, with higher values associated with more diversified rotations. PCA and cluster analysis successfully integrated both datasets, identifying five distinct ecological profiles that combine specific nematode signatures with enzymatic activities. Kriging of the principal components allowed the spatial visualization of these patterns. In conclusion, the nematode community and enzymatic activity are sensitive and complementary bioindicators. Their integrated assessment provides a robust tool for diagnosing soil health and biological quality in sustainable agricultural systems, being strongly influenced by the diversification of crop rotations.