Research purpose: To assess enzyme-mediated feedbacks to increases in nutrient availability from long-term fertilization.
Location of sampling: Belowground Plot Experiment
Frequency of sampling: Monthly for soil extracellular enzyme activities.
variable measured: Activities of extracellular enzymes: Beta-glucosidase, cellobiohydrolase, N-acetylglucoaminidase, leucyl aminopeptidase, acid phosphatase, and phenol oxidase. Soil chemistry: Total carbon and nitrogen and gravimetric water content.
laboratory methods: Soil samples from each plot were collected as composites of four 2 cm diamter, 15 cm deep soil cores.
form of data output: Extracellular enzyme activities were measured using short-term, room temperature assays with fluorometric organic substrates (Saiya-Cork et al. 2002, SBB 34(9): 1309-1315.; Zeglin et al. 2013, Ecology 94(10): 2334-2345.). Total carbon and nitrogen were quantified using thermal conductivity. Gravimetric water content was measured by drying soil samples overnight at 105 Celsius and weighing water mass loss.P
quality assurance: -999 or NA were used for quality control / quality assurance.
instrumentation: FilterMax F5 Multimode Microplate Reader; Flash EA 1112 NC Analyzer