CONTENTS. XXV11 



III. Biological action of lime . ' . . . . . .459 



Action of lime on nitrogenous organic matter . .460 

 Recapitulation . . . . . . . . .461 



CHAPTER XXL INDIRECT MANURES GYPSUM, 

 SALT, ETC. 



Gypsum ........... 462 



Mode in which gypsum acts . . . . . .462 



Salt 465 



Antiquity of the use of salt . . . . . . 465 



Nature of its action ........ 465 



Salt not a necessary plant-food . . . . . .466 



Can soda replace potash ? . . . . . . .466 



Salt of universal occurrence . . . . . .467 



Special sources of salt . . . . . . .468 



The action of salt 468 



Mechanical action on soils . . . . . . .470 



Solvent action . . . . . . . . .470 



Best used in small quantities along with manures . .472 

 Affects quality of crop . . . . . . .472 



Rate of application 473 



CHAPTER XXII. THE APPLICATION OF MANURES. 



Influence of manures in increasing soil-fertility . . .474 

 Influence of farmyard manure on the soil . . . .475 



Farmyard manure v. artificials ....... 476 



Farmyard manure not favourable to certain crops . . . 477 

 Conditions determining the application of artificial manures . 477 



Nature of the manure . . . . . . .478 



Nitrogenous manures . . . . . . . .478 



Phosphatic manures . . . . . . . .480 



Potash manures ......... 480 



Nature of soil .......... 481 



Nature of previous manuring . . . ... . . 482 



Nature of the crop ......... 483 



Amounts of fertilising ingredients removed from the soil by 

 different crops ......... 484 



Capacity of crops for assimilating manures .... 486 



Difference in root-systems of different crops . . . 488 



