Student name Institution Course name Submission date How soil particles sink in water This soil is a mixture of the clay sand and silt. The soil particles in the “soil bottle” sank slowly and took long to settle. The mixture took long to settle because of the different sizes of the particles. The sand settled at the bottom because it has the biggest size while the clay settled on intra‐particle diffusion and soil pH increase." European Journal of Soil Science 65.1 (2014): 149-161. Rinkes Zachary L. et al. "Interactions between leaf litter quality particle size and microbial community during the earliest stage of decay." Biogeochemistry 117.1 (2014): 153-168. Xu Guoce Zhanbin Li and Peng Li. "Fractal features of soil particle-size distribution and total soil nitrogen distribution in a typical watershed in the source area of the middle Dan River China." Catena 101 (2013): 17-23. [...]
PROJECT: SOIL PARTICLES You have learned that soil is made of weathered rock, water, air, and organic material. The size of particles is an important soil characteristic. According to the United States Department of Agriculture (USDA), there are three main particle sizes—sand, silt, and clay. Clay is particles smaller than 0.002 mm. Sand is particles larger than 0.05 mm. Particles in between are silt. The size of particles in soil determines how much water the soil will hold. Small particles hold more water than large particles. Soil usually settles into different layers called horizons. The arrangement of horizons is the soil profile. In this experiment, you will observe how particle size affects the soil profile. OBJECTIVES Describe how particle size affects the settling of soil. Materials 1 1/2 cups potting soil 1/2 cup sand 2 wide-mouthed juice bottles with lids Masking tape Pen Spoon Water Directions Make masking tape labels for each juice bottle. Label one "soil" and the other "soil and sand." Fill both bottles 3/4 full of water. Slowly pour 1 cup of soil into the water in the "soil" bottle. Observe the behavior of the soil particles. Fill the "soil" bottle the rest of the way with water. Secure the lid tightly and shake the bottle. Put the bottle on a flat surface where nothing will disturb it. Add the 1/2 cup of sand to the remaining 1/2 cup of soil. Mix thoroughly with the spoon. Slowly pour the sand and soil mixture into the water in the "soil and sand" bottle. Observe the behavior of the particles. Fill the "soil and sand" bottle the rest of the way with water. Secure the lid tightly and shake the bottle. Put the bottle on a flat surface where nothing will disturb it. Leave both bottles undisturbed overnight. Look at the bottles the next day. Record your observations. Questions What did you notice about the way the soil particles sank in the water? How was it different from the way the soil and sand particles sank? What does the soil look like in the "soil" bottle? How is it different from the soil in the "soil and sand" bottle? In the "soil and sand" bottle, which type of soil is on the bottom? Why? The amount of each size particle in soil is the particle size distribution. Do you think this is a good way to determine particle size distribution? Why or why not?