An experimental probe-type injector was developed to inject liquid fertilizers into the soil at discrete intervals with minimal soil disturbance. A prototype injector was designed using data obtained with an instrumented probe that monitored the dynamic response of soil subjected to impact loading. Since dynamic soil conditions varied from field to field, dynamic soil properties were further monitored with a resonant column instrument to aid the prediction of dynamic soil penetration resistance. The prototype injector employed a unique mechanical mechanism, a hydraulic based actuator system, and a liquid flow timing device to insert a probe into the soil and simultaneously inject liquid. The probe motion resulted in minimal amounts of soil disturbance so that the injection process was performed without stopping the tractor at each injection interval. An evaluation of the prototype revealed that the injection interval could be varied from 200 to 600 mm without significant soil disturbance for a soil penetration depth of about 65 mm.