The Effectiveness of a Microbiological Attribute as a Soil Quality Indicator Depends on the Storage Time of the Sample

Abstract

The aim of this study was to analyze the effect of storage time on the main microbiological attributes used as soil quality indicators. Seven attributes were evaluated (microbial biomass carbon; microbial basal respiration; fluorescein diacetate hydrolysis—FDA; and the activity of the enzymes urease, β-glucosidase, arylsulfatase, and acid phosphatase) in four different soil environments (clayey soil in forest, sandy soil in forest, clayey soil in coffee field, and sandy soil in coffee field). Each attribute was quantified at five different storage times (15 h and 15, 30, 60, and 120 days). The values of FDA, microbial biomass carbon, and arylsulfatase declined significantly in the first 15 days of storage. Therefore, these attributes should be evaluated soon after soil collection. The values of microbial basal respiration declined on day 30; therefore, it should be evaluated up to day 15 of storage. The decline in urease values varied depending on soil texture; therefore, the shortest storage period, 15 days, should be considered. The values of β-glucosidase declined only on day 120. Therefore, soil samples can be stored for up to 60 days for determination of this enzyme. Acid phosphatase activity was not affected by storage time. Depending on storage time, all the attributes were able to differentiate the soil environments. Long storage times compromise the use of most of the attributes as soil quality indicators, as well as their usefulness in discriminating soil environments. Therefore, storage times should be considered when these attributes are used as soil quality indicators.