84 THE PRINCIPLES OF AGRICULTURE 



leaves, pomace, are generally more valuable 

 for the improving of the texture of the soil 

 than for the direct addition of jDlant-food. If 

 the soil is loose, dry and leachy, or if it is 

 very hard, compact and retentive, these ma- 

 terials may benefit it. To determine the value 

 of such materials in plant -food, one must con- 

 sult tables of their composition in books ; and 

 the more thoroughly the}^ are rotted, the more 

 available are their constituents. 



SUOGESTIOJSrS ON CHAPTEB V 



108a. "The proportion of roots to tops [in clovers] varies 

 widely. The medium red clover, one year from seeding, gives 

 a much larger proportion of roots to tops than clover two years 

 from seeding. Red clover which produces two tons per acre 

 may be expected to furnish potentially to the soil, after the 

 first cutting, in roots and stubble, 40 to 60 pounds of nitrogen, 

 20 to 25 pounds of phosphoric acid, and 30 to 50 pounds of 

 potash. Thirty bushels of wheat * * * and 2,700 pounds 

 of straw, would remove approximately 46 pounds of nitrogen, 

 20 pounds of phosphoric acid, and 26 pounds of potash." — 

 Eoberts, ^^ Fertility of the Land," 345. 



109a. Accessible discussions of green -manuring are to be 

 found in Chap, xiv., "Fertility of the Land;" pp. 117-123, Voor- 

 hees' "Fertilizers." Cover-crops in relation to fruit-culture are 

 discussed in pp. 184-202 of Bailey's "Principles of Fruit-Grow- 

 ing," and in other books and recent bulletins. 



Ilia. Intensive farming is "high-culture" farming. It is 

 farming on a comparatively small scale, when the laud is kept 

 constantly in productive crop, with the best of tillage, and the 

 free use of manures and fertilizers. The Innd is forced to its 



