80 SOILS AND THEIR USES 



7. Test the value of air in soils by growing two lots of corn in two pots, 

 one under favorable conditions of reasonably loose soil, and the other using 

 heavy clay soil which has been puddled by mixing when very wet and the air 

 has been almost entirely driven out. The air may be excluded by keeping the 

 clay soil very wet. In wet seasons such adverse conditions are often found 

 in low spots of corn or cotton fields. 



8. Soil Collection. Make collections of all the t} r pes of soils available. 

 Classify these and put the proper labels on them. 



9. Soil Grains. -If microscopes are available, study the soil grains of 

 clay, silt and fine sand. Compare them as to size and as to their tendency to 

 cling together. 



10. Soil Analysis. We may analyze a sample of soil in a crude way by 

 placing, say, ten grams or j^ oz. in a bottle of water. Pour off all the water 

 into another bottle, or drain it off with a glass siphon, leaving the coarsest 

 sediment in the bottom of the first bottle. Shake the second bottle a few times 

 and allow it to stand for thirty seconds and draw off the water into a third 

 bottle, leaving a finer sediment in bottle Number 2. Continue this separation 

 of the soil until nothing but the finest clay is left in the water. If we wish to 

 determine the exact amount of soil of each degree of fineness, the water from 

 each may be evaporated, and the grains may be carefully weighed. Compare 

 this with the table showing the sizes of soil particles given in this chapter. 



11. Comparative Study of Soils. Obtain several samples of soil from 

 different fields. Rub a bit of each sample between the thumb and finger and 

 decide as nearly as possible which sample contains the most clay and which 

 the most sand. Which seems to contain the most organic matter. For this 

 purpose the fingers should be wet as each sample is examined. 



12. Soil Types. The school should provide itself with samples of soil of 

 each of the great soil types. A bulletin describing the soil types of America 

 may be obtained from the Bureau of Soils, United States Department of Agri- 

 culture. Send for samples of these soils by writing to friends or prominent 

 teachers who live in each of these soil areas. The samples may then be used 

 for comparative study and in contrast with the soils in the vicinity of the school. 



QUESTIONS 



1. Describe what soil really is. 



2. What are the advantages of organic matter in the soil? 



3. What are the effects of bacteria in soils? 



4. Describe an exercise to show the difference between a sterilized and an 



unsterilized spot of soil. 



5. Describe the method of soil inoculation. What other methods are there? 



6. Of what importance is air in soils? 



7. Give some idea of the range in size of different soil grains. 



8. Name the kinds of grains in order of size. 



9. What are the agencies at work in the movement of soil? 



10. What are some of the special uses of sandy soils and sandy loam? 



11. Give the special adaptations of heavy clay loams. 



12. What family of plants is best adapted to limestone soils? 



13. Tell briefly what you can of the Fargo clay loam. 



14. Where is Marshall silt loam found? What crops are suited to this region? 



15. Tell what you can of Carrington loam and its uses. 



16. Tell what you can of Miami clay loam and its uses. 



References. U. S. Farmers' Bulletins: 245, Renovation of Worn-out 

 Soils. 257, Soil Fertility. 494, Lawns and Lawn Soils. Soil Laboratory 

 Manual, Eastman & Davis, J. B. Lippincott Co., Philadelphia Soils, Their 

 Properties and Management, Lyons. Fippin and Buckman, The Macmillan 

 Co., N. Y. Soil Physics and Management, Mosier and Gustafson, J. B. Lippin- 

 cott Co. 



