296 THE PRINCIPLES OF SOIL MANAGEMENT 



154. Leguminous crops. Most of the leguminous 

 crops are deep-rooted and are vigorous feeders. Their 

 ability to acquire nitrogen from the air makes the use 

 of that fertilizer constituent unnecessary except in a 

 few instances, such as young alfalfa on poor soil, where 

 a small application of nitrate of soda is usually bene- 

 ficial. Lime and potassium are the substances most 

 beneficial to legumes on the majority of soils. 



155. Root-crops. Many of the members of this 

 class of crops will utilize very large amounts of plant- 

 food if it is in a form in which they can use it. Phos- 

 phates and nitrogen are the substances generally re- 

 quired, the latter especially by beets and carrots. 



156. Vegetables. In growing vegetables, the object 

 is to produce a rapid growth of leaves and stalks rather 

 than seeds, and often this growth is made very early in 

 the season. As a consequence, a soluble form of nitrogen 

 is very desirable. Farm manure should also have a 

 prominent part of the treatment, as it keeps the soil in a 

 mechanical condition favorable to retention of moisture, 

 which vegetables require in large amounts, and it also 

 supplies needed fertility. The very intensive method 

 of culture employed in the production of vegetables 

 necessitates the use of much greater quantities of 

 manures than are used for field crops, and the great 

 value of the product justifies the practice. 



157. Fruits. In manuring fruits, with the exception 

 of some of the small, rapid-growing ones, it is the aim 

 to maintain a continuous supply of nutrients available 

 to the plant, but not sufficient for stimulation, except 

 during the early life of the tree, when rapid growth 



