132 FIRST PRINCIPLES OF AGRICULTURE. 



sess a loose-branching system. A mixture of the tuft 

 and loose-growing grasses is, as a rule, better than either 

 singly. 



Pood Requirements. The chief object in the growth 

 of grasses is to obtain the nutrition contained in leaf 

 and stem in the form of pasture, forage, or hay. Nitro- 

 gen, which promotes this form of growth, is an important 

 constituent, and it is essential to provide a liberal sup- 

 ply, either directly, as nitrate of soda, or in organic forms, 

 which decay more or less rapidly. 



The grasses resemble the cereals in their power of ac- 

 quiring mineral food ; hence clay soils, which are rich 

 in the minerals, are naturally well adapted for their 

 growth. Except when seed is grown, or hay is sold, 

 the grasses are not regarded as exhaustive crops. 



Clovers. The clovers are grouped with the grasses 

 because usually grown for the same purpose, for pas- 

 ture, forage, or hay. They, however, belong to a family 

 of plants which possesses characteristics very different 

 from the grasses, both in reference to method of growth 

 and composition of product. The varieties usually grown 



are: 



Scarlet or Crimson Clover, an annual. 



Red or Broad Clover, a biennial. 



Alsike or Swedish Clover, a triennial. 

 White or Dutch Clover, a perennial. 



Of these the red and white are more extensively grown 

 than the others. 



Methods of Growth. The red, alsike, and crimson 

 clovers all possess a tap-root which penetrates downward 

 to considerable depths ; and as it descends it throws out 

 root-fibres into the different layers of soil ; these gather 



