Development, construction, and field evaluation of a soil compaction profile sensor

Studies have shown that an increased level of soil compaction leads to a reduction in infiltration characteristics of soil, which in turn leads to low soil moisture. Conventional methods of measuring soil compaction are tedious, time consuming, and expensive. The objective of this study was to develop and evaluate a soil compaction profile sensor (SCPS) that could assist in the assessment of the state of compactness of the soil profile in real-time. The device developed in this study consisted of eight cutting elements, designed to provide information on soil resistance to cutting for every 7.5 cm layer down to a total depth of 60 cm. The design produced a sensor with a backward-sloping rake angle and a total thickness of 5.1 cm. Extensive field tests were conducted during summer and fall of 2001 and spring of 2002 in loamy, clayey, and sandy fields. Within each soil type, three different moisture conditions were included in the test (low, medium, and high). Analysis of the test data revealed that the soil cutting force was a function of soil bulk density, moisture content, and the location of the cutting element within the soil profile. Additional analyses were conducted to relate soil cutting force profile to the cone index profile. The empirical relationship between predicted and measured profile sensor output had a coefficient of multiple determination (R ²) of 0.977, indicating that the SCPS can potentially be used to make real-time measurements of soil strength profile.