F. Gholamzadeh, H. Asgarzadeh, H. Khodaverdiloo, M.r. Mosaddeghi,
Volume 28, Issue 1 (5-2024)
This study was conducted in the summer of 2021 to evaluate and validate the gravimetric soil water content measurements using a field oven. Ten soil types with a salinity of saturated paste (ECe) less than 4 dS m-1 and three saline soils were studied around Urmia Lake. Plots with dimensions of 1 m × 2 m were prepared for the selected soils to measure gravimetric soil water content and soil physical and chemical properties. The gravimetric water content (θm) values measured using the field oven (i.e., θmFO), were compared with those measured by a standard lab oven (i.e., θmLO). The soil water content values measured in the lab, regarded as a benchmark, were measured at 105 °C for 24 h. Temperatures of 120, 140, and 160 °C with three durations of 10, 15, and 20 min were used to dry the soil samples in the field oven. There was very good compatibility between the values of θmFO and θmLO when the soil samples were dried in the field oven for 15 or 20 min at all three temperatures. Significant linear relations were obtained between the θmFO and θmLO values as the slopes of linear relations were close to 1, the intercepts of relations were negligible and the distributions of measured data around the line 1 to 1 were unbiased. The minimal effects of soil organic matter content, clay content, salinity, and bulk density on water content measurements by the field oven indicate an important advantage of this method. These results confirm the high efficiency of the field oven for fast and reliable measurements of water content in different soils.
