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Soil is Important! Soil is the link between the rocky crust of the Earth and all life on the Earth’s surface. It is a subsystem of the Earth that is very important, because all life on Earth depends on soil (directly or indirectly) for food. All soil contains minerals, organic matter, water, and air.

Organics Bacteria and fungi in the soil will break down dead plants and animals. This makes organic matter to the soil. Organic matter dissolves in the water in the soil to provide nutrients to plants. Soils with less than 2% organic matter are rated “low”; “medium” soils have 3-10%, and “high” soils have over 10% organic matter. TO LAB v3/experiments/soil/img /soil%5BHR%5D.jpg

Measuring Organics 1.Mass a crucible. 2.Add the 2 spoonfuls of dry soil from the other part of your team and mass again. 3.Set up a ring stand with a clay triangle and Bunsen burner like in the diagram. 4.Start the Bunsen burner on low, and gradually increase the flame until the crucible glows red. 5.Heat for 5 minutes at red-hot. This will burn off all the organic matter. 6.Turn off the Bunsen burner and let the crucible cool. 7.Mass the crucible and burnt soil. Calculate the mass of the dry soil & the burnt soil. 8.Calculate how much organic matter was burnt away. 9.Calculate the % of organic matter in your soil by: % = (mass of organic matter)/(mass of dry soil) x 100 THIS IS DONE AFTER SOIL MOISTURE!

Moisture Plants need water, and they also need the nutrients that dissolve in water. We can measure both how much water is in the soil when we collect it (moisture content) as well as how much water your sample can hold onto (moisture holding capacity). Soils with less than 5% water content are rated “low”, “medium” soils have 6-20% water, & soils over 20% water are rated “high”. TO LAB background

Measuring Moisture: Part 1 1. Get a small metal can. 2.Use a rubber band to fasten a filter paper over one end of the can. 3.Mass the can-and-filter. 4.Add the soil and mass again. 5.Put the can-and-soil into a drying oven set at 100°C for at least 24 hours. 6.Mass the soil and can again. 7.Calculate the mass of the original and the dry soil. 8. Calculate how much water was lost while the soil was dried in the oven. 9.Calculate the moisture content of the soil as follows: moisture content(%) = (mass of lost water/mass of dry soil)x100

Measuring Moisture: Part 2 1. Put the can with the dry soil into a large beaker. 2. Add water until its halfway up the sides of the can. 3.Let it sit for at least 24 hours. 4.Put the can and wet soil on a wire gauze screen on a ring stand (see diagram) and let it drain into a sink for 30 minutes. 5.Mass the can and wet soil. 6.Calculate the mass of the wet soil. 7.Calculate the mass of water the soil absorbed. 8.Calculate the moisture holding capacity of the soil by: (mass of water absorbed)/(mass of dry soil)x100

Temperature Temperatures below 5°C are too cold for plants to grow, and at these temperatures even soil bacteria and fungi are barely active. All plants grow best at temperatures from 16-22°C. Between 5-16°C some plants will grow. Above 22 °C its too hot for almost all plants to grow.

pH pH is a measure of how acidic or basic the soil is. This depends on the kind of rock the soil is made from, the kinds of plants that decay, and the amount of rainfall. Lots of rain usually removes calcium and makes the soil acidic. Decaying oaks and maples make soil basic, while decaying evergreens (except pines) make the soil acidic. Most plants prefer soils with a pH between but will tolerate a range of 6-8. When the soil becomes too acidic (lower than 6) bacteria don’t grow well. TO LAB Which would make an acidic soil?

Measuring pH 1.Measure out 2.0 grams of soil for pH into a small beaker. 2.Add 10 mL. of distilled water. 3.Stir well with a clean glass stirring rod. 4.Set up a funnel and filter paper like the diagram. 5.Stir up the soil-and-water mix and pour it quickly into the filter paper. 6.Test the filtrate (the liquid that goes through the filter paper into the beaker) with pH paper.

Texture Good soil has both air spaces and solid particles. The air spaces provide room to store and move water & air as well as room for root hairs to grow. The solid particles provide nutrients for plants and water storage. Soil texture describes the sizes of the particles in the soil. Soils are usually a mixture of pebbles (2-6 mm), sand ( mm), silt ( mm) and clay (under mm). Sandy soils let water flow and drain quickly. Clay soils absorb water slowly and don’t drain well. TO LAB How many textures do you see? / Dendro_Images.h tml

Measuring Texture 1.Look at your soil sample with your eyes and also with a magnifying glass. Do you see mostly clay, sand, or pebbles? 2.Get the sieve set. Make sure the largest screen size is on top, and that the sizes decrease from top to bottom. 3.Put your sample of soil in the top sieve. Hold the sieves upright and shake hard for 30 seconds. 4.Pour out the soil from each sieve onto a separate pieces of paper, recording the sieve’s screen size. The particles in each sieve are larger than the screen size for that sieve, but smaller than the next biggest screen. 5. Give the sieve set to another group. 6.Mass each portion of soil. 7.Calculate the total mass of your soil sample. 8.Calculate the % of soil in each size range by: % = (mass of soil of this size)/(total mass of soil)x100