ENRICHING THE SOIL FARM RESOURCES 79 



(c) cover -crops, which are sown late in the 

 season for the purpose of protecting the soil 

 during winter as well as for green -manuring. 



110. Green -manuring crops may be again 

 divided into those which gather nitrogen and 

 those which do not, or those which have the 

 power of using the nitrogen (see Chapter vi.) 

 of the air, and those which obtain all their 

 nitrogen directly from the soil. The nitrogen - 

 gatherers leave their nitrogen in the soil, when 

 they decay, for the use of other plants. The 

 nitrogen -gatherers are the leguminous plants, 

 or those which belong to the pea family, as 

 all kinds of peas and beans, clovers, alfalfa, 

 vetch. The other class, or nitrogen -consumers, 

 comprises all other plants used for green -ma- 

 nuring, as rye, oats, rape, mustard, buckwheat, 

 maize. 



111. In general, the best green -manure crops 

 are the legumes, red clover for the North, 

 alfalfa for dry regions, cow -peas and Japan 

 clover for the South. With the exception of 

 the cow -peas, these crops require one or more 

 seasons for full development, and, therefore, 

 cannot be used in intensive farming. 



2b. The management of green -manures 



112. The ideal green -manuring is that which 

 is a part of a regular rotation, the green- 



