The daily water consumption of a wheat culture was quantified on an Oxisoil using atmospheric and soil data measured automatically on an experimental farm in Ponta Grossa, Paraná, Brazil. The measurement period was August through December 2003. The rain contribution to soil moisture and the vertical upward movement of water within the soil were particularly emphasized. Our results show that in the evaluated period (a) wheat evapotranspiration amounted to 6.75 mm a day, to which upward water flux contributed with 62 %; (b) soil water-budget evaporation lags behind Penman evapotranspiration estimates by about 7 days, as if the soil responded to atmospheric variations with a weekly delay; (c) as expected, rain significantly affected soil storage and usually raised evapotranspiration rates, and (d) given the fact that the mean matric potential in the root zone was near the critical value for wheat, the conclusion was drawn that irrigation would have potentially beneficial impacts on wheat in this region; more water would be available and higher levels of evapotranspiration warranted, which is desirable from the agricultural viewpoint.
evapotranspiration; irrigation; soil water budget
