Fluorescein Diacetate: A Potential Biological Indicator for Arid Soils

Abstract

A field study was undertaken to identify a potential biological indicator for arid soils. The study area covered five districts (111,681 km2) in which annual rainfall varied from 217 to 427 mm and soil texture ranged from sandy to clay loam. The surface 30 cm of arid soil from agricultural field sites differing in soil properties and cropping pattern were used in the study. Soil physicochemical, microbiological, and biochemical parameters (pH, EC, organic C, total N, available N, total P, mineral P, available P, phosphate solubilizing bacteria, arbuscular mycorrhizal fungi, nitrifying bacteria, microbial biomass, acid and alkaline phosphatase, phytase, dehydrogenase, and fluorescein diacetate (FDA) hydrolysable enzymes) were identified as indicators of soil quality. Ten of the 12 parameters studied exhibited significant correlation between FDA hydrolysable enzyme activity and the other enzyme activities (acid phosphatase, alkaline phosphatase, phytase, dehydrogenase). A strong linear regression (R2 = 0.61; p < 0.01) between the FDA hydrolysable enzyme activity and microbial biomass was observed. The results demonstrated that FDA hydrolysable enzyme activity is a potential biological indicator of arid soils and is a better indicator than dehydrogenase activity, already considered as a biological indicator.