A SOIL PROBE like this is used to sample the soil. It is pushed into the ground an a soil core about 12 inches long and 3/4 inch wide is pulled out. That soil sample can then be sent in to the NDSU Soil Testing Lab for analysis. Before putting fertilizer on the field, we need to know what is already in the soil so we know how much to apply for the crop to flourish without putting on too much. Excess fertilizer can cause environmental problems.