Determinação do bulbo molhado em nitossolo vermelho distroférrico utilizando-se a técnica de TDR, em laboratório.

Abstract

Since water is the most important natural resource to agriculture and to existence of humanity in general, to prevent unneeded water use, localized irrigation method has been largely applied in the world. To design the trickle irrigation systems adequately, designer must identify the water front position in the soil profile, any time after beginning to apply water from a punctual water source. Then, they dimensions were measured at a NITOSSOLO VERMELHO Distroférrico profile, using a TDR technique to measure soil moisture. The used outflows had been of 2.4; 3.6 and 4.8 L h-1 for 8 hours of application and volume of 19.2; 28.8 and 38.4 liters, respectively. Lysimeter of PVC with dimensions of 1.10 x 1.00 x 0.90 m was constructed and was install TDR probes to each 5 cm of low for top and to each 10 cm in the surface. The results showed that wetted front position in space, after water application (depth x diameter) was, in average 0.76 x 0.45 m, 0.92 x 0.65 m and 0.96 x 0.81 m for the outflows of 2.4, 3.6 and 4.8 L h-1, respectively. TDR techniques can be used to identify, with adequate precision, the wetted front in the soil profile, during application of water from punctual source.