10 LABORATORY MANUAL OF AGRICULTURE 



1. Sandy soils. Made up chiefly of the soil constituents 

 of the sand size. 



2. Clay soils. Soils that contain over one third clay 

 and a large amount of silt. 



3. Loam soils. Soils made up of about one half sand of 

 the various grades and the other half silt and clay. 



The soil particles vary in color and shape as well as in 

 size. The color of the soil particles has but little influence 

 on the color of the soil. The color is due to organic matter 

 and other coloring material found in the soil. 



Equipment. 1. Microscope magnifying to low power. 



2. Microscope slides. 



3. Four large test tubes. 



4. A few grams of the following soils : gravel, sand, loam, 

 clay. 



Directions. Place a few grains of the gravel on a piece 

 of white paper and examine with reference to color. 



Estimate the per cent of particles that are white, gray, 

 brown, black. Record your results in the accompanying 

 outline form. 



Study the shape of the particles and determine the per 

 cent that are angular and rounded. Record your obser- 

 vations. 



Study the condition of the particles. Are they single or 

 compound ? Record the percentage of each. 



Divide the particles into groups as to size. Record the 

 per cent that are coarse, medium, and fine. 



Place a few grains of sand on a microscope slide and study 

 under the microscope, making the observations required in 

 studying gravel. Study in the same way the sample of 



