Especially today��s machines such as powerful tractors, combine harvesters etc. which are becoming heavier because of their additional attached equipment, have become a reason maybe for high level of soil compaction observed in agricultural fields. Another reason for soil compaction is tillage in non-suitable terms of the soil. In addition to these external effects, natural effects such as excessive rainfall and drought can also be a reason for high levels of soil compaction [1�C3].Soil compaction can be defined as a function of the specific weight and humidity of the soil. During compaction, soil particles get closer each other and a diminishing of the entrapped air is seen. As a result; an increase is seen for soil bulk density and soil penetration resistance [4,5].

Soil compaction has also a negative effect Inhibitors,Modulators,Libraries on the physical, chemical and biological properties of the soil. This negative effect limits roots growth and the plants cannot complete their growth properly. Hence, less yield and economic losses are seen. In addition to this, the machines, which are operating on the compacted soil need extra energy [6,7]. Therefore, the determination of the soil penetration resistance level is quite important for sustainable production, yield and conservation of the farmland. It also has a place in the precision farming approach, which promises that the field performance could be tracked, mapped and analyzed down to the square meter level so that farmers can know how well or poorly each part of a field is producing [8].In the scientific literature, two Inhibitors,Modulators,Libraries different methods are used for measuring soil penetration resistance.

In the first method, soil samples are taken over the field at a certain depth of soil with the help of an open-ended pipe and then the samples are analysed in the laboratory to determine the penetration resistance. On the other method, a specifically sized Inhibitors,Modulators,Libraries conical tip is immersed Inhibitors,Modulators,Libraries into the ground vertically. The cone is sunk into the ground at a standard rate, starting at the soil surface of the soil [9]. The tip angle of the cone is 30��. Soil penetration resistance is calculated AV-951 by dividing the force needed to insert the cone into the ground at a standard speed of 30 mm/s by the base area of the cone. This calculated value of the cone is called the cone index (CI) and is expressed by Equation (1) [10]:CI=F/A.

(1)where CI: Cone index [MPa], F: Force [N], A= Base area [mm2].To determine the cone index of the soil, cone penetrometers are used. Generally, static and dynamic inhibitor supplier penetrometers are used in the applications. The cone acts perpendicular to the surface in both methods. The difference between the two methods lies in how the force to insert the cone into soil is provided.In the static method, the cone is pushed into the ground. To achieve this mechanical, hydraulic or electrical power can be used.