68 BULLETIN 355, U. S. DEPAETMENT OF AGEICULTURE. 



(a) Place about three tablespoonfuls of soil in a clean dish and moisten to a thick 

 mud with clean, soft water. With a clean stick separate the mud into two portions 

 and lay on one portion a piece of blue litmus paper. Press the other portion of wet 

 soil down on the litmus paper; leave for five minutes, then carefully remove the upper 

 portion of the soil and examine the paper. If it has turned pink or pink spots appear 

 upon it the soil is acid. 



(b) Place one piece each of red and blue litmus j^aper in the bottom of a drinking 

 glass. Over this place white blotting paper or filter paper, upon which put three or 

 four tablespoonfuls of soil. Now add clean rainwater slowly until the paper becomes 

 damp. After 10 or 15 minutes note whether a change has occurred in the color of 

 the litmus paper. If the blue litmus paper has changed to a pink color, the soil is 

 acid. 



Compare this test with (a) to determine which method is preferable. 



(c) Repeat test (a) or (b) on other soils. Save one of the acid soils for the next 

 exercise. 



Lime is used to correct acidity in soils (Ref. No. 1, p. 251). — Place about three table- 

 spoonfuls of acid soil in a clean dish and thoroughly mix with it about a quarter of a 

 teasponful of air-slaked lime. Moisten the mixture and test with blue litmus paper 

 as before. What effect did the lime have on the acid soil? 



REVIEW QUESTIONS, LESSON IX. 



1. How can acidity in soils be detected? 



2. What are the objections to soil acidity? 



3. Name some legumes that can tolerate soil acidity. 



4. Describe lime carbonate, quicklime, and water-slaked lime. 



5. Explain how lime neutralizes acids in soils. 



6. WTiy is it undesirable to use quicklime in excessive quantities on light, sandy 

 soils? 



7. Discuss the relation of the fineness of pulverized limestone to the rate of applica- 

 tion. 



8. Describe three ways in which the application of ground limestone to a very poor 

 acid clay soil may be of benefit. 



9. When a soil is neutral or alkaline in reaction, what may be implied? 



10. What becomes of the lime supply of soils? 



LESSON X. MANAGEMENT OF SPECIAL SOILS. 



The successful management of any soil depends on an understand- 

 ing of its special characteristics. Its weak points must be recog- 

 nized and corrected if possible, and crops which are best adapted 

 to the soil should generally be grown. Among the soils which 

 require special management are the sands, the clays, and marsh lands. 



SANDY SOILS. 



Sandy soils are low in water-holding capacity, are subject to being 

 blown by the wind, and are low in elements of plant food. 



Moisture of sandy soils. — Low water-holding capacity of sandy 

 soil has been explained in discussing the relation of texture to the 

 amount of moisture soils can retain. Moreover, small differences in 

 the texture of sandy soils or the influence of small quantities of 

 organic matter considerably increase the total amount of ^yater held 



