12 BULLETIN 521, U. S. DEPARTMENT OF AGRICULTURE. 
carefully studied. Each sample should be designated by a letter or 
number to correspond with one in the report. 
Record and report: Notes should be made of the time and place of 
the taking of the samples as well as detailed observations, as sug- 
gested above. If the sample is taken in uncultivated land, the nature 
of the native vegetation should be noted. If taken in a cultivated 
field, whatever is known of the previous cropping should be noted 
and those crops named which appear in the district to be best suited 
to the type of soil. The lay of the land and the nature of the under- 
lying strata should be noted wherever possible. A written report 
should accompany each section of samples. 
Note. — It will be useful in connection with both class and laboratory work to 
have as an exhibit in the agricultural museum columns of the representative 
types of the soils of the school district. These columns may vary in length 
from 1 to 10 feet, according to the depth of the soil. Glass tubing 1 to 2 inches 
in diameter may be secured for this purpose. Separate jars for each foot of 
soil should be used in collecting and for laboratory samples. Pint fruit jars 
serve well for this purpose. 
Lesson 11. — Relation of Soil Type to Crops. 
1. Adaptation of crops to soil. 
2. Crops suited to leading soil types. 
Illustrative material: Leading soil types of district. (To be used in 
Lesson 12 also.) 
Lesson 12. — Management of Soil Types. 
1. Management of light soils. 
2. Management of heavy soils. 
Exercise 9. — A Comparative Study of Soil Types. 
Purpose: To study further the effects of the chief soil ingredients 
upon the physical nature of soils. 
Directions: Secure samples of clay soil, sandy soil, loam, and leaf 
mold on the same day and keep dry in bottles until used. Note the 
color of each. Weigh 4 ounces of each sample and spread in shallow 
pans until thoroughly dry, then weigh again. The difference in 
weight of the sample before and after drying represents the amount 
of moisture which can be removed in ordinary evaporation. Take 
1 ounce of each of the dry samples and heat at a high temperature 
in an iron pan or a large iron spoon until everything that will burn 
has disappeared. Weigh each sample again. The difference in 
weight will show approximately the amount of organic matter in 
each. Rub each sample with the fingers and examine with a hand 
lens, noting the comparative fineness of grains. Make about 1 ounce 
of each sample plastic with water and note comparative stickiness. 
Mold each of these samples into a ball, put away to dry, and then 
note effect. of drying upon its plasticity. Saturate a small canful of 
each sample with water, put away to dry, noting how long it takes 
each sample to dry and to what extent there has been shrinkage. 
