Soil moisture, percent organic matter and soil texture calculations

Soil Moisture Procedures 1. Weigh the soil when it is taken out of the ground. 2. Dry it in the oven. 3. Weigh the soil after it is dry. 4. Consider drying the soil more and reweighing the soil to be sure it is dry.

Soil moisture calculation Percent moisture = mass water x 100 mass original soil

Calculate the percent of soil moisture Masses of soil and the pan +/-0.005 Mass of original soil + pan 180.00 Mass of dry soil + pan 150.00 Mass of empty pan 20.00

Percent water Percent water = 30.00/160.00 x 100 = 19%

Percent organic matter in the soil Grind dry soil into small particles Put a sample into a dry, weighed crucible Weigh the crucible and the soil Heat to burn the soil Let it cool Heat the crucible and the soil Reweigh Repeat until the mass no longer change

Percent Organic Matter

Percent Organic Matter Why must the soil be dry before heating? Why is the soil heated in a crucible? Will the mass of the soil increase or decrease?

Percent organic Why does the soil need to be heated repeatedly until the mass no longer changes?

Percent organic equation Percent organic = mass organic matter x 100 mass of original, dry soil

Percent organic calculation Masses of crucible and soil +/-0.005 g Mass of crucible and soil 25.00 Mass after first heating 23.50 Mass after second heating 23.00 Mass after third heating 23.00 Mass of dry empty crucible 5.00

Percent organic calculation Percent organic = 2.00/20.00 x 100 = 10.0 % organic matter

Soil Texture Soil texture depends on the amounts of sand, silt and clay. Sand is the largest type of particle Silt is intermediate in size Clay is the smallest Gravel is removed first..

Soil texture Soil texture depends on the amounts of sand, silt and clay in the soil. Size description Diameter in mm Clay < 0.002 Silt 0.002-0.06 Sand 0.06-2

Sand – the largest particles

This is also sandy soil

Silty soil

Clay soil – the smallest particles

Porosity The amount of space between the particles. More porous soils have space for more air.

Soil Permeability: The ability of water to flow through soil.

Water holding capacity: the ability of the soil to hold water Clay stores too much water Sand does not hold water very well

Water logging: Clay soils easily become water logged

A heavy clay soil when dry

Water logging When the soil becomes too wet Plants can die from growing in water logged soils Clay soils can become waterlogged easily.

Water logged field

Compare sand, silt, clay Which is the most porous? Which has the highest water-holding capacity? Which is the most permeable? Which has the best drainage? Which has the most air space?

Workability: Workable soil is good for agriculture and gardens

Loam Soil Loam soil is a mixture of sand, silt and clay It is good for agriculture because it has a range of properties from all of the particle types.

Loam A mixture of 40% sand, 40% silt and 20% clay

Soil Texture test

Compare the sand, silt and clay

Soil texture calculations Percent sand: 15% Percent silt: 60% Percent clay: 25% Determine the soil texture Silty Clay Loam

Soil Texture calculations: Percent sand: 70 Percent silt: 20 Percent clay: 10 Determine the texture of the soil.

Soil Texture calculations: Percent sand: 70 Percent silt: 20 Percent clay: 10 Determine the texture of the soil.

Soil Texture calculations: Percent sand: 70 Percent silt: 20 Percent clay: 10 Determine the texture of the soil.

Soil Texture calculations: Percent sand: 70 Percent silt: 20 Percent clay: 10 Determine the texture of the soil. Sandy loam

Sandy Loam

Soil texture calculations Percent sand: 20% Percent silt: 30% Percent clay: 50% Determine the soil texture

Soil texture calculations Percent sand: 20% Percent silt: 30% Percent clay: 50% Determine the soil texture

Soil texture calculations Percent sand: 20% Percent silt: 30% Percent clay: 50% Determine the soil texture

Soil texture calculations Percent sand: 20% Percent silt: 30% Percent clay: 50% Determine the soil texture Clay

Clay Soil

Properties of clay, sand, silt and loam Texture Porosity Water flow Water holding Aeration Workability clay low poor Good (too much?) silt medium sand high good loam Best

Soil Texture Experiment Grind the soil sample with a mortar and pestle. Weigh the sieves and put them together correctly. Shake the soil sample to separate the particles. Pull the sieves apart. Weigh the sand, silt and clay. Add to find the total mass. Calculate the percent of sand silt and clay Use a soil texture triangle to classify the soil texture.

Soil Texture Lab Report Data collection: Data TABLE with a descriptive title, units, ranges of uncertainties for the units Qualitative Observations! (colour…) Data Processing: The equation used and a sample calculation Data Presentation: A labelled table with the results.