Assessing the Spatial Distribution of Phosphatase Enzyme Activity Across Two Agricultural Landscapes.

Enzyme activity has been previously used as an indicator of environmental quality, nutrient pool status, and the biochemical potential of soil ecosystems. The goal of this study was to assess the activity of the hydrolytic phosphatase enzymes (alkaline phosphatase [APA], acid phosphatase [ACP], and phosphodiesterase [PD]) across two agricultural landscapes in relation to other physiochemical parameters using geostatistical and spatial analyses.  APA activity at site 1 varied from 5.85 to 0.10 µmol p-nitrophenol g^-1 soil h^-1; ACP varied from 6.05 to 0.85 µmol p-nitrophenol g^-1 soil h^-1; and PD varied from 3.09 to 0.31 µmol p-nitrophenol g^-1 soil h^-1.  At site 2 APA varied from 6.22 to 6.06·10^-3 µmol p-nitrophenol g^-1 soil h^-1; ACP from 3.95 to 4.32·10^-3 µmol p-nitrophenol g^-1 soil h^-1; and PD from 3.24 to 2.38×10^-3 µmol p-nitrophenol g^-1 soil h^-1.  Ordinary Kriging models were fit to semivariograms based upon the descriptive data measured. Method performances were assessed by calculating the root mean square error (RMSE) standardized, mean standard error (MSE).  Information on patterns of spatial structure allowed for the interpretation of results in relation to the landscape structure/use that could not be provided by conventional statistical analysis.