AN AUTOMATED SAMPLING SYSTEM FOR MEASURING SOIL pH

Within the scope of precision farming there is a need for improved methods of assessing and managing soil variability. The site-specific management of soil pH is one application that has potential benefits for crop production. However, current grid sampling and mapping techniques to estimate lime requirement may not be adequate. For this reason, an automated soil sampling system for measuring soil pH on-the-go has been created. The system includes a computer-operated soil sampling mechanism mounted in a shank, a global positioning unit, and a pH meter with a flat surface electrode. The system measures soil pH directly on a sample. The automated soil sampling system can determine pH while taking soil samples at a selected depth (0-20 cm) every 8 s. A simple linear regression was used to calibrate the electrode mV output against soil pH obtained via a standard laboratory method. Field testing yielded an r2of 0.83 and a standard error of prediction of 0.45 pH.