Desempenho de sistemas de leitura de tensiômetro em condições de temperatura controlada

Abstract

The study aimed at assessing alternative systems to the mercury vacuum for quantification of water matric potential, to define the time for restoring the equilibrium between the water tension in the interior of the tensiometer, and in the soil after the insertion of the needle in the tensiometer, and to quantify errors in the determination of the water matric potential and the soil moisture from the alternative systems. The essay was carried out in pots in the laboratory. Three tensiometers were installed per pot, six replications, at depths of 0.20, 0.35 and 0.50 m. After the definition of the equilibration time, the matric potential and volumetric moisture were compared in the three systems. It was concluded that after the insertion of the needle of the tensiometer the reading can be performed in any of the times from 30 to 180 seconds; The tensiometer replaces the mercury vacuum gauge from saturation to field capacity and the Bourdon vacuum gauge from the condition at or near the field capacity to the driest condition; and the errors resulting from alternative systems were reflected in the estimation of the soil moisture whereas the alternative systems underestimated the values from the field capacity.