of manures. 



VII MANURES SI 



manure that can be used by the planter. Special uimttires, 

 which are sometimes called artificial, on the other hand, 

 contain one or more of the necessary constituents of plant 

 food, and they are used when it is found that these consti- 

 tuents have been removed from the soil by heavy cropping, 

 or do not originally exist in the soil in sufficient quantity. 

 Baron Liebig laid down what he styled the " Law of Mini- Lieblg's law 

 imnns^'' by which he meant that the crops are governed by 

 the niinimiun of one, or several, of the inorganic elements 

 of plant food. A soil may contain in excess all the necessary 

 constituents for plant growth except one, and if that one be 

 supphed artificially the fertility of the soil is ensured. The 

 application of a manure containing a plentiful supply of the 

 one deficient substance, shows the principle of special or 

 artificial manures ; but it shows, also, the necessity of 

 accurate knowledge of the soil and of plant life, in order to 

 determine what ought to be the exact composition of the 

 artificial manure the planter proposes to make use of. The 

 indiscriminate and ignorant use of these manures frequently Indi? 



Uscnmi- 



does permanent harm to the soil, without increasing the manures ° 

 crops ; and then they entail an outlay in money that brings ^l'^^ ^°^^ 

 no profit, and that often causes loss. 



General Manures may be divided into three classes, 

 namely^ — i. Farm yard manure. 2. Green crop manure. 3. 

 Waste products. 



Faf'?n yard manicre consists of litter (straw, cane trash, 

 &c.) which has been trodden down by horses, cattle, 

 pigs or sheep in stables, cowsheds, pigsties and pens, and 

 mixed with the solid and fluid excrements of the animals. 

 It is the most valuable manure that can be put on the land, Value of 

 for it enriches the soil more than any other substance can manure! 

 do, it exerts a beneficial chemical , as well as mechanical 

 effect on the land, and no other manure is so lasting in its 

 action. Its quality, and therefore its effect on the soil, varies 

 greatly according to the animals producing it and the kind 



E 2 



