Several instruments using technology from other industries have been developed for measuring soil nutrient levels at the farm. Some of the instruments use ion selective electrodes to measure the pH, nitrate and potassium levels of the soil. Another instruments measures the transmittance of light through leaves to provide an indication of plant health and tissue nitrogen levels. These instruments are relatively inexpensive and can help a farmer who is considering site specific crop management gain confidence in this new crop technology at a low investment. This would prepare him for use of real time measurement technology when it becomes available.