Development of a mechanical transducer for real-time soil tilth sensing

The development of real time and continuous sensing systems for soil properties provides a valuable tool to obtain inexpensive and rapid information about the soil current status and future management of soil in the context of precision agriculture. This study aimed to design a simple transducer for soil tilth detection by determining dynamic strain behaviour of commercially available spring tines. The dynamic characteristics of the tines were determined using simple strain gauge circuits from which the response from coarse, intermediate and fine tilths was investigated. The acquired signals were analysed using digital signal-processing techniques. The results of the signal analyses were correlated with the results of standard sieving. The results showed that the amplitude of the signals was a valuable parameter to determine clod size. The mean weight diameter of the tilth grading curve could be determined to within±6.3 mm of that determined by mechanical sieving. It was found to be independent of the soil textures for the clay loam and sandy loam studied. The technique requires the depth of operation to be held constant. The direction of operation when operating both across and along the direction of mouldboard plough was found to have a very minor effect.