142 FARM AND SCHOOL PROBLEMS. 



the tree ; phosphorus is essential to the development of the seeds, 

 and nitrogen gives to the leaves their green and healthy color. 

 The tree must be fed a balanced ration. 



Culture. There are three methods of culture known to 

 orcharding. These are cover-crop culture; mulching; and sod- 

 culture. 



Cover Crops. 



A cover crop is one that is sown for the purpose of being 

 turned under the following spring. 



The use of a cover crop as determined by various experi- 

 ments in orchards are as follows : 



1. A cover crop checks the growth of trees in late summer. 



2. It thus protects trees from early frosts. 



3. It takes up soluble plant food that would otherwise leach away 

 during winter and spring. 



4. It acts as a blanket, holding snow and preventing root injury. 



5. It adds humus to the soil when plowed under. 



6. Clover, vetch, cowpeas, soy beans, are good cover crops. 



There are two distinct classes of cover crops 



(a) Those that die in the fall as, cowpeas, soy beans, 

 turnips, rape and buckwheat. 



(b) Those that live over winter, as, clovers, vetches, rye, 

 .and alfalfa. 



Group (a) makes a larger growth and is probably best for 

 soil fertility. 



Group '(b) furnishes the best protection to roots, and soil 

 during cold weather. 



Question Which plants among the above named groups are- 

 nitrogen gathering plants? Which are not? 



Mulching. 



This method of culture consists in keeping the orchard in 

 grass which may be cut late in the spring and spread under the 

 trees in a circle reaching just beyond the tips of the branches. 

 Any coarse vegetable matter may be used for mulching. It may 

 be spread upon the ground to a depth of from four to six 

 inches. This may be done every year or every other year. 



