CONTENTS IX 



CHAPTER X. 



Commercial Fertilizers. — History of development of industry ; 

 Complete fertilizers and amendments ; Variable composition of 

 commercial fertilizers ; Preparation of fertilizers ; Inert forms 

 of matter in fertilizers ; Inspection of fertilizers; Mechanical 

 condition of fertilizers ; Forms of nitrogen, phosphoric acid, 

 and potash in commercial fertilizers ; Misleading statements on 

 fertilizer bags ; Estimating the value of a fertilizer ; Home mixing ; 

 Fertilizers and tillage ; Abuse of commercial fertilizers ; Proper 

 use of ; Field tests ; General principles ; Preliminary experiments ; 

 Verifying results ; Deficiency of one element ; Deficiency of two 

 elements ; Will it pay to use fertilizers? Amount to use per acre ; 

 Influence of excessive applications ; Fertilizing special crops ; Com- 

 mercial fertilizers and farm manures. Pages 205-224. 



CHAPTER XI. 



Food Requirements of Crops. — Amount of fertility removed by 

 crops ; Assimilative powers of crops compared ; Way in which 

 plants obtain their food ; Cereal crops ; General food requirements ; 

 Wheat ; Barley ; Oats ; Corn ; Miscellaneous crops ; Flax ; Pota- 

 toes ; Sugar-beets ; Roots ; Turnips ; Rape ; Buckwheat ; Cotton ; 

 Hops ; Hay and grass crops ; Leguminous crops. Pages 225-237. 



CHAPTER XII. 



Rotation of Crops. — Object of rotating crops ; Principles involved 

 in crop rotation ; Deep and shallow rooted crops ; Humus-consu- 

 ming and humus-producing crops ; Crop residues ; Nitrogen-consu- 

 ming and nitrogen-producing crops ; Rotation and mechanical 

 condition of soil ; Economic use of soil water ; Rotation and farm 

 labor ; Economic use of manures ; Salable crops ; Rotations advan- 

 tageous in other ways ; Long- and short-course rotations ; Problems 

 in rotations ; Conservation of fertility ; Necessity of manures ; 

 Uses of crops ; Losses of fertility with different methods of farming ; 

 Problems on income and outgo of fertility from farm. Pages 238- 

 254. 



References ; Experiments ; Review Questions ; Corrections. 

 Pages 255-272. 



