Depth of penetration of a soil coulter is obtained using a sensor being mounted on the side of the disk adjacent the edge such that the sensor as the disk rotates is located above the surface of the soil during a first part of its rotation and is located below the surface during a second part of its rotation. This sensor is also used to detect characteristics of material outside the coulter as it rotates and temperature. This data is used in a growth model to generate predicted growth data to allow control of growth remediation materials to the crop.