movement in horizontal and upward directions in the soil it may improve its chances of reaching the insect pest present in the soil. The pattern of movement of any insecticide, besides being controlled by its chemical nature, is also dependent upon the soil texture. No research work has been reported on the movement of chlorpyriphos in different directions in loamy sand soils. Therefore, the present experiment was conducted to study its movement in such a soil occurring at the research station at Durgapura, Jaipur (India). MATERIALS AND METHODS Movement of chlorpyriphos was studied during winter 1997 in a loamy sand soil comprising about 83.3% sand, 8.9% silt, 7.9% clay and 0.2% organic carbon. The soil pH W a S 7.8. The experiment plot size used was 4 m x 5m. In the centre of each plot an area of 40 cm x 90 cm was marked. To study the horizontal and downward movement of chlorpyriphos from this earmarked area of each plot, a 5 cm deep soil was removed evenly and chlorpyriphos was placed at the exposed bottom at the rate of 2 g a.i. per 40 cm x 90 cm area in a thin layer after mixing with soil. The pit was then filled back with the earlier dug soil to the level of the rest of the plot. Similarly, to. study the upward movement of chlorpyriphos the central core of the marked plot was dug upto 15 cm depth where the insecticide was placed in the same manner and filled back with soil to level. All the three kinds of treatments had one untreated control as check and there were three replications in the experiment. The initial soil samples were drawn on