EFFECT OF TRACTOR WHEEL COMPACTION ON BULK DENSITY AND INFILTRATION RATE OF A LOAMY SAND SOIL IN SAUDI ARABIA
A field study evaluated the effect of tractor wheel compaction on soil bulk density and infiltration rate of a loamy-sand soil. The study was conducted at different two sites in the Kingdom of Saudi Arabia. Mean soil bulk density ranged between 1.55-1.79 g cm-3 at the first site and 1.44-1.75 g cm-3 at the second site under different tractor wheel compactions. Soil bulk density increased proportionally with repeated compaction and was related to soil moisture contents at the time of application of compaction force. However, mean cumulative water infiltration ranged between 1.53-5.79 cm hr-1 and the mean infiltration rate of soil between 1.32-5.70 cm hr-1 in different compaction treatments. Among the various compaction treatments, the "4-passes" treatment caused 69 % reduction in infiltration rate of soil. The highest compaction treatment (8-passes of tractor wheel) caused up to 77 % reduction in infiltration rate of soil. Soil bulk density and infiltration rate of soil were highly correlated (r=0.887). The difference in soil bulk density and infiltration rate of soil was significant among all the compaction treatments when compared to the control treatment (zero-pass). The research findings showed an excellent potential for improving the physical properties of light textured soils to achieve higher irrigation efficiency if simply tractor (highly used conventional agricultural implement) coupled with other commonly adopted tillage practices are used for soil compaction.