A Soil Sampling Mechanism for On-the-Go Analysis and Mapping of pH and Other Properties

The use of GPS-aided technology to apply inputs site-specifically has a significant potential to improve the use of fertilizers, lime, and other materials. One of the main factors limiting the effectiveness of this technology is the problem of accurately assessing the input requirements of the field. In the most common approach, soil samples are acquired on a 2.5 acre grid pattern, sent to a laboratory for analysis, and various interpolation methods are applied to the sample results in order to predict the values for the entire field. Studies have shown that soil properties often have spatial variability greater than 2.5 acres, however the costs of sampling and lab analysis preclude denser sampling. A promising approach to this problem is to use devices that measure soil properties on-the-go more intensively than 2.5 acres/samples. One such sensor was prototyped by Purdue University for sensing soil pH. It demonstrated that soil pH could be successfully measured in-situ using combination, ion-selective electrodes. For this device to be viable, research must be conducted to create a soil sampling mechanism that can acquire soil in a wide variety of soil conditions and at commercially acceptable operating speeds.