Improved effectiveness and efficiency in measuring soil enzymes as universal soil quality indicators using microplate fluorimetry

We tested the relevance of the microplate fluorimetric (F) assay for five enzymes in contrasting land uses, including woodland, grassland, cultivated and contaminated lands, as compared to the standard spectrophotometric (P) method. Enzymatic activity measured by the P method ranged from 0 to 56.04 nmol-pNP g−1 min−1 (median = 4) while the F method revealed lower values ranging from 0 to 6.22 nmol-MUB g−1 dry soil min−1 (median = 1). The values obtained by the P method were around 8 times higher than those revealed by the F method. However, the F method revealed significant differences in enzyme activity in orchard parcels (land use with low variations in soil properties). We concluded that the F method improves the effectiveness and the efficiency of measuring universal soil quality indicators using enzymes.