MANURES AND FERTILISERS. 23 



THE FUNCTIONS OF MANURES. 



Nitrogen. The general effect produced by the 

 application of some single element of plant food is 

 fairly well marked, and is a guide in determining 

 what material should be applied or made to pre- 

 dominate in manuring individual crops. Nitrogen is 

 the substance chiefly concerned in vegetative growth 

 that is, in the production of leaves, shoots, and stems 

 and it is the material to apply when a rapid or in- 

 creased growth of these is desired, or when a crop lacks 

 vigour and presents a stunted yellowish appearance. 

 While it is necessary for all vegetables it is particularly 

 beneficial to green crops, and to those that depend 

 for their ultimate development on the production in 

 the early stages of a strong, vigorous leaf growth. On 

 the other hand, a predominance of nitrogen would 

 probably be more or less injurious to certain vegetable 

 crops such as those grown for their tubers, bulbs, 

 and seeds the more so if the other plant foods were 

 very deficient in the soil. 



Phosphates. These play an important part in 

 the early development and root growth of young 

 plants. They have the power to counterbalance the 

 excessive absorption of nitrogen from the soil, and 

 tend to promote a sturdy, firm type of growth. 

 Phosphates are closely associated with the formation 

 of tubers, flowers, fruits, and seeds. As phosphates 

 are so important, and are usually lacking in soils, their 

 liberal and regular use should be more generally 

 adopted. 



Potash. This substance assists greatly in the 

 development of thick, healthy leaf growth, and is 



