This implies a reduction in soil volume by reducing the voids in between soil particles. As a consequence water and air is displaced and soil bulk density increases, resulting in a reduced permeability for water and air. Susceptibility of soil to compaction depends on several factors, which influence soil particle interactions:   Soil compaction can occur naturally by the drying and wetting process called soil consolidation, or when external pressure is applied to the soil. The most relevant human-induced causes of soil compaction in agriculture are the use of heavy machineries, tillage practice itself, inappropriate choice of tillage systems, as well as livestock trampling. Use of large and heavy machineries for agriculture often causes not only topsoil but subsoil compaction. Subsoil compaction is more difficult to be regenerated than topsoil compaction. Not only may the weight of machineries i.e. axle load, but also velocity and number of passages affect the intensity of soil compaction. Inflation pressure of wheels and tyres also plays an important role for the degree of soil compaction. Whether heavy machinery is in use or not, tillage practice itself can cause soil compaction. While the major cause of soil compaction in a tillage activity nowadays is due to machineries, the influence of compaction resulting from lighter equipments and animals to the topsoil should not be neglected. Moreover, inappropriate choices of tillage systems may cause unnecessary soil compaction. It should however be noted that tillage activity could reduce topsoil compaction compared to no tillage activity in the long term. Significant livestock trampling resulting from livstock farming on meadows and agricultural land is also viewed major cause of soil compaction. This is not affected whether the grazing is continuous or short term, however it is affected by the intensity of grazing. Major effects on soil properties due to soil compaction are reduced air permeability and reduced water infiltration. Main physical negative effects to plants are restricted plant root growth and accessibility of nutrients due to increase in bulk density and reduced soil pore size. This may lead to an extremely dry topsoil and eventually causes soil to crack because the roots absorb water requiring for transpiration from the upper part of the soil where plants can penetrate with their restricted root depth. Soil chemical properties are influenced by change in soil physical properties. One possible effect is a decrease in oxygen diffusion that causes anaerobic condition. Together with anaerobic condition, increases in soil water saturation can increase denitrification processes in the soil.