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 SoU Tyye to Crops. 



1. Adaptation of ci'ops 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 Avith 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. 



