The results of a theoretical-experimental research aimed at constructing a tank-truck prototype designed and constructed by the Authors and specifically used to spread olive oil extraction plant effluents on cropped soil are presented. The transverse distribution was investigated through comparing the test data with the mathematical modelling. The experimental data quite closely follow the theoretical ones, with average values of the volume delivered by each nozzle, quite similar to each other in almost all the investigated cases. On the other hand, for application rates much lower than those most frequently used in olive orchards, (30 m3/ha), less regular conic jets are possible near the spreading valves. In view of that, the obtained results, though in agreement with the scarce literature available, have shown that the valves designed to allow a uniform transverse distribution can be optimized both from the mechanical and geometric point of view. Instead, the longitudinal distribution study highlighted no special critical working conditions of the machine; in fact, the recycling regulating system proportional to the advancing speed, allows having response and regulation time of less than 1.0 s in all the investigated volumes. Only 50-80 s before full emptying the tank, equal to around 4% of the total working time, high deviations were observed for applied volumes close to the maximum values.