326 MANAGEMENT OF CLAYS AND DEPLETED SILT LOAMS 



with little or no attention given to the maintenance of their fer- 

 tility. As a rule, these soils are low in organic matter and nitrogen, 

 they are commonly acid, and are in need of available phosphorus. 

 Liming is usually the first step to be considered in their improve- 

 ment, the object being, mainly, to improve the conditions for grow- 

 ing clover and other legumes. Plowing under legumes is recognized 

 as the best method to increase the organic matter and nitrogen. 

 Manure, when available, generally gives good returns when 

 applied to the clover fields. Liberal applications of soluble phos- 

 phates should be made to the grain and cultivated crops. Acid 

 phosphate is generally considered the best phosphate fertilizer to 

 use in beginning soil improvement. Later on, when improvements 

 shall have been well advanced, rock phosphate may take the place 

 of the acid phosphate. A short rotation including clover is also 

 an important factor to be considered in the regeneration of these 

 soils (Chapters XII, XIII, XV). 



Field Studies. 1. Select a run-down farm and make careful observations 

 as regards general appearance, weeds, character of crop growth, and soil 

 conditions. Suggest remedies. 



Home Projects. Select three acres of depleted silt loam, or an acre, and 

 divide into three equal portions. Fertilize properly. Establish a three-year 

 rotation, corn, grain and clover. Plow under the first crop of clover, and always 

 the second growth. Students may continue the rotation for at least six years, 

 and note soil improvement. 



Other rotations suited may be substituted, or may be conducted in addi- 

 tion to the one suggested. 



QUESTIONS 



1. Compare clay soils with sands in their workability and texture. What 



is " gumbo'"? 



2. Name the special problems in the management of clays. State briefly 



their solutions. 



3. Discuss drainage in relation to clay management: (a) benefits; (6) 



methods; (c) depth of tile, fall, "blinding," distance apart to lay lines 

 of tile. 



4. Discuss tilth in relation to clay management. 



5. How may the organic matter and nitrogen in clay soils be increased? 



6. What special fertilizer do clays commonly require? What is the relation 



of lime to fertilizer needs on some clays? 



7. What is erosion and how does it affect clay lands? Name some means 



of prevention. 



8. Describe a good method for clearing stumpy clay lands. 



9. Name crops that are particularly adapted to clay soils. Crops that can 



be grown successfully on good management. What crops are not 

 adapted to clays? Why? 



10. Name two good rotations for dairy-farming on clay land. A rotation for 



grain-farming. 



11. Discuss the improvement of depleted silt loams. 



12. What crops have you observed growing on very heavy clay soils? 



13. See outline summary of this chapter in table of contents. 



