Este trabalho teve como objetivo avaliar as características de desempenho do equipamento de irrigação pivô central operando em condições de campo e também analisar o comportamento da agua abaixo da superfície do solo quanto a uniformidade de distribuição. Para tanto utilizaram-se os coeficientes de uniformidade de Christiansen e de distribuição calculados conforme metodologia proposta por MERRIAN e alii (1973) e também com dados de umidades do perfil de solo em três profundidades. O pivô foi ensaiado em três velocidades 20, 40 e 60% com a linha lateral em duas posições sendo uma em nível e a outra em aclive. Os resultados obtidos mostram que em todas as profundidades os coeficientes de uniformidade foram superiores aos obtidos acima da superfície os valores dos coeficientes de uniformidade aumentaram com o tempo em todas as profundidades, os altos valores alcançados pelos coeficientes de uniformidade abaixo da superfície do solo mostraram que a uniformidade subsuperficial pouco depende da uniformidade acima da superfície

The objective of this research was to evaluate the performance characteristics of a center pivot irrigation equipment operating at field conditions and analyze the under the surface of the soil water behavior in regard to its distribution uniformity. The performance of the system was evaluated by Christiansen uniformity coefficient (CUC) and the coefficient of uniform distribution (CUD). Both were calculated from precipitation data collected according to the method of MERRIAN et alii (1973) as well as with moisture data from the layer of the soil at three depths. The experiments were conducted on the campus of Universidade Estadual de Maringá. Paraná, in a Red Earth (Paleudult) type of soil. The center pivot was tested at 20%,40% and 60% velocities with the lateral line at level and 5,78% upward. The equipment of irrigation operated with all emissaries opened and with ten of them clased in order to obtain high and low values of coefficient of uniformity. Those values were compared to those from the under the surface of the soil. The results of this research all owed the following conclusions: the Application Potencial Efficiency reduced with the increase of the ambient temperature and the reduction of the air reIative humidity; - the coefficients of uniformity were always greater for conditions under the surface of the soil than for conditions above it; -the under the surface of the soil coefficients of uniformity increased with time, at all depths investigated; - the high values obtained by the under the surface of the soil coefficients of uniformity in short periods of time, even in those tests where the uniformity of the water supplied to the surface was low, indicate that the uniformity under the surface of the soil is almost independent of the above, the surface of the soil uniformity