The objective of this work was to evaluate the efficiency of ceramic capsules from the State of Ceara, Brazil, and from the United States, as well as, to test the performance of the pressure transducer coupled in the air chamber tensiometer in field conditions, in two different depths, in the quantification of the matricial potential of the water in the soil, in comparison with those of the conventional tensiometers (mercury manometer). The field work was accomplished in Mossoró, in the State of Rio Grande do Norte, Brazil, using a 2 x 2 x 2 experimental design in completely randomized blocks the factor being: origin of the capsules; tension measurement and depths. Measurements were accomplished in a period of 40 consecutive days. It was verified that in the field tests the origin of the capsules provided same tension values, although the capsules from Ceara state presented higher conductance than the ones from USA. The tension values obtained by the instruments of tension measurements differed statistically, although the difference was within the precision (1.0 kPa). A high correlation exists among the tensions obtained by the two instruments of tension measurement.
tension measure; tensiometers; irrigation management
