52 Effective Farming 



EXERCISES 



1. Soil constituents. Place a handful of loam in a tall bottle or 

 a mason jar ; nearly fill the vessel with water and shake for several 

 seconds, then allow the soil to settle. What can you say of the sizes 

 of the mineral particles of this soil? 



Also, place a few grains of rich garden soil on an asbestos-covered 

 screen and heat until the soil becomes red hot. Does an odor result ? 

 What are you burning out of the soil? 



2. Types of soil. Write to the Chief of the Bureau of Soils at 

 Washington for a soil survey pamphlet of your county, if one has 

 been issued. Study the maps and descriptions in this pamphlet. 

 Visit, if possible, each of the soil types and collect samples and classify 

 them according to name. Examine each of the soil types for color and 

 texture. What kinds of crops are usually grown on each soil type? 

 Were you choosing a farm in your county which type would you select ? 



3. Water in soil. Place a small quantity of air-dry soil in a test 

 tube and heat carefully over a gas or alcohol flame. Moisture will 



collect on the sides of the tube. This mois- 

 ture was held largely in the soil as hygroscopic 

 water. 



Arrange four lamp chimneys as shown in 

 Fig. 21. Using two of the chimneys, place 

 dry clay soil in one and dry sand in the other 

 so that the soil stands at the same height in 

 bo * ot *" Hace empty tumblers beneath 

 each and pour the same quantity of water 

 into the tops. Record the time required for water to drip from each 

 tube. What force caused the water to percolate? What form of soil- 

 water dripped from the tubes ? Compute the water in each tube after 

 dripping has ceased. Which soil retained the more water ? 



Arrange the other tubes as just directed and place the bottom of 

 each in a tumbler partly filled with water. Record the, time necessary 

 for moisture to reach the top in each kind of soil. What force caused 

 the water to rise against gravity ? What form of soil-water is in these 

 tubes ? How much water was taken into the soil in each tube ? Try 

 this experiment with long glass tubes. Explain the results. 



Place a quantity of sand in a pan and gradually let water drop on 

 the sand at one side of the pan. Eventually, all the soil in the pan be- 

 comes wet. What force carries the water ? 



4. Soil mulch. Place sand in two chimneys and on the sand in 

 one place a layer of fine, dry soil. Leave the other uncovered. Place 



