Spatial cross-correlation between physicochemical and microbiological variables at superficial soil with different levels of degradation

Best soil management practices can be achieved by evaluating the spatial cross-correlation variability of soil microbiological and physicochemical indicators, in order to comprehend the underlying relations between these mutually dependent properties, being valuable indicators for prospective evaluation of soil resources. The purposes of this study were to measure microbiological and physicochemical variables in superficial soil, spatially cross-correlate and determine spatial causalities between these two families of variables. The spatial variability of pH, gravimetric soil water content, U-238, Th-232, K-40, Cs-137, acid phosphatase, dehydrogenase activity, microbial biomass carbon, mesophilic aerobic bacteria and filamentous fungi was studied at a 13 ha field located in Uruguay. U-238 and Th-232 were both negatively lineally correlated with gravimetric soil water content (-0.42), Cs-137 (-0.45 and -0.48 respectively) and dehydrogenase activity (-0.44 and -0.48 respectively). A semivariogram analysis revealed that the best fit model for soil variables was spherical, with moderate to strong spatial dependence. Cross-correlation results suggest that there is an influence factor from spatial interaction. In this sense, gravimetric soil water content connects physicochemical variables with soil biodiversity. Spatially, soil water content is inversely influenced by Th-232 and U-238 (as indicators of sub-superficial soil), and directly influenced by dehydrogenase activity (indicator of soil microbial activity), revealing soil microbial activity as a possible indicator of water retention in drying soils. The combination of spatial patterns of environmental radionuclides with microbiological indicators of soil quality could represent a valuable integrated approach to assess soil conservation status and further explain the impact of anthropogenic disturbance.

Automated summary

The study measures microbiological and physicochemical variables in superficial soil, and demonstrates spatial correlations and causalities between these variables. The results reveal connections between soil water content, environmental radionuclides, and soil microbial activity, highlighting the importance of soil management practices. The combination of environmental radionuclide patterns and microbiological indicators offers a holistic approach to evaluate soil conservation status and anthropogenic disturbance impacts.