The AgraTronix Soil Compaction Tester allows you to check your soil for hardpan quickly and easily, regardless of the soil type. Benefits of soil compaction testing are increased yield by increasing root and plant development, increased effectiveness of fertilizers, pesticides, and herbicides, and increased soil water retention. The color-coded, liquid-filled dial reads in pounds per square inch of pressure it takes to penetrate the soil- Green testing range (0-200 psi): good growing conditions, Yellow testing range (200-300 psi): fair growing conditions, and Red testing range (300 psi and above): poor growing conditions.