Soil moisture is measured by Time Domain Reflectometry (TDR). TDR measurements integrate soil moisture over 0-15 cm depth in the mineral soil only and are made once each day on dates when soil respiration is measured. TDR data have been collected since 1993.

Data:

YEAR = year collected
DOY = Day of year
TRTMT = treatment
SM = Soil moisture expressed as average cc H₂O per cc soil by treatment
sem = + 1 standard error of the mean, calculated as: [standard deviation (sample) of the mean /square root of n]
N/A = data not available
nd = calculation not done