This research aimed to evaluate center pivot performance as a function of wind speed (VV), relative humidity of air (UR) and mean air temperature (T) and establish a stochastic model to estimate application efficiency as a function of these independent variables. Data were collected, during the morning and the afternoon period, and during three times of the year (August, 12 and 13; September, 22 and 23; and October, 27 and 28, 2005), considering two speeds of outer driver unit (50 and 100%). A randomized block design was used for factor speed of outer driver with factor time of the year as a split plot of factor speed, and considering period of the day as replication. The mean pressure head at the end of the lateral was 137.3 kPa and close to the value predicted by the dealer of 127.5 kPa. The average water depths applied were 12 and 5.7 mm for 50 and 100% speed, respectively. Calculated Christiansen's uniformity coefficient (CUC) provided values considered in literature as standard. Average water depths collected in the morning period were greater than the ones collected in the afternoon. VV, T and UR independent variables influenced significantly water application efficiency values.
uniformity coefficient; distribution efficiency; application efficiency; irrigation efficiency
