<b>Evaporation distribution in greenhouse using three evaporation heights</b>

Abstract

The management  of  irrigation water  in  a  culture  is fundamental,  because  it  allows  the  rational  use  of  this factor  of production  aiming  to  obtain  the maximum output per unit of water applied.  Allied to this technology, protected  environment  cultivation  allows  continuous production  in periods which  conditions  in  the field  are usually unfavorable,  enabling the supply of the domestic market in all seasons. In order to know the meteorological variables that most affect the production in this environment, it was made a research in the experimental area of the Department of Rural Engineering of the Universidade Estadual Paulista - UNESP, campus of Botucatu, to evaluate the spatialization of the protected environment by the distribution of minievaporimeters to verify the energy distribution in three heights, 40, 80 and 120 cm from the ground. The work was conducted in greenhouse, with guidance Northwest Southwest.  It was performed the measuring of the evaporation of minievaporimeter weekly, for 6 months. The minievaporimeter spatial distribution showed that the period of study of 07 May to July 16 of 2005 had an increased of the evaporation in the environment to 40 cm from the ground, that is, during the coldest months. The period from July 30 to September 16 of 2005 the greatest evaporation occurred at 80 cm from the ground. The minievaporimeters installed to 120 cm from the ground had values less than or equal, the other heights, regardless of the evaluation period.  The Southwest face had higher evaporation for the entire study period. There was greater evaporation in the protected environment during the coldest months of the year for minievaporimeters which were close to the ground.