TITLE: The Effect of Soil Texture on Percolation
AUTHOR: Gregory T. Nachtrab
SCHOOL: Marian High School
SCHOOL ADDRESS: 273 Union Avenue, Framingham, MA 01701

In this project I investigated the factors that affect percolation in soils. Eight locations representing different soil types were tested. Percolation rate was measured by measuring the rate of flow in a 75 mm hole at a depth of 500 mm. Soil samples from each location were evaluated for composition, pH, and the fraction of coarse, medium, fine, very fine sand and clay and silt fractions. The percolation rate was found to increase as the percent of coarse sand increased, and decreased as the percent of very fine sand, clay and silt increased. There was not significant effect that could be attributed to either pH or composition within the range of soils tested. The correlation between any single component of the soil was not good. However, by taking the ratio of coarse sand to very fine sand, clay and silt a good correlation was found. This effect can be explained by the fact that the coarse sand increases the amount of porosity which makes drainage easier, while the very fine sand, clay and silt all decrease porosity and make drainage more difficult.