• A five-point penetrometer with GPS for measuring soil compaction variability 

      Fountas, S.; Paraforos, D.; Cavalaris, C.; Karamoutis, C.; Gemtos, T. A.; Abu-Khalaf, N.; Tagarakis, A. (2013)
      Measuring soil compaction is a factor of interest to monitor soil fertility, which plays an important role in crop production cycle. Soil penetration resistance is the most commonly used method to measure soil compaction. ...