MANURES 45 



crop will also require a smaller quantity of each 

 of the other ingredients, or the balance of plant 

 food in the soil will be upset. For example, if 

 corn receives a good dressing of nitrates in the 

 form of nitrate of soda, it will take from the 

 soil a corresponding amount of phosphates and 

 potash to meet its increased growth, and to 

 allow for this one must supply phosphates and 

 potash along with the nitrate of soda or the soil 

 will become unduly depleted of them. Or the 

 soil may not have enough to meet the demand, 

 and so the nitrate of soda is wasted, as it can 

 produce no extra growth if enough of the 

 other constituents are not available to help it. 



The actual quantities of manures to be 

 applied to different crops will vary with the 

 nature of the soil, and will have to be regulated 

 accordingly. The quantities mentioned in the 

 last chapter are typical examples for securing 

 full crops on average soils. Manurial experi- 

 ments and chemical analysis of the soil furnish 

 the most reliable information as to what 

 manuring is required for the different crops. 



We have seen that dung is the mainstay 

 of the fertility of the soil, therefore it is 

 necessary to make the most of it, and thereby 



