against the wheat or corn plant, where the roots are left in the soil 

 and add to the store of humns. In order to preserve the balance, 

 the nurserynian is obliged to do one of two things — he must prac- 

 tice a rotation which will keep up this supply, or he is obliged to 

 constantly seek new land. It is due to this fact that large (pianti- 

 ties of fruit stocks and nursery trees are grown in the new lands of 

 the western plains country. 



^i cover-cro]) Is a crop sown in the orchard at the close of tJie till- 

 age season, to produce a s upply of humus, to promote nitrification, 

 to prevent the leaching and eroding effects of fall and spring rains, 

 and to protect the roots of the trees fronn excessive cold. — The cover- 

 crop is one of the most important factors in successful orcharding 

 at the present time. Orchard cultivation has been urged for a 

 number of years ; it has been practiced in many localities and the 

 results obtained have encouraged orchardists to continue the prac- 

 tice ; but clean cultivation has its limitations and must not be carried 

 too far. It should apply only to the growing season of tlie tree. 

 The ground at that time should be in a perfect condition of tilth. 

 The dust blanket should be so thoroughly maintained that the film 

 moisture of the soil is completely preserved. In this condition the 

 soil furnishes a favorable seed-bed, and even small seeds may be 

 expected to germinate successfully. 



The cover-crop is sown in mid-summer and is expected to pro- 

 duce a mat of surface vegetation that will cover the ground thickly 

 before autumn comes. One of the difficulties in growing cover- 

 crops is to obtain a good " catch." If the orchard has not been 

 thoroughly cultivated a good catch is hard to secure. On the other 

 hand, if tillage has been thorough there is usually no trouble in 

 obtaining a good stand. As a rule the smaller the seed, the more 

 uncertain the catch. Why ? Small seeds should not be covered 

 deeply. They are therefore more at the mercy of external condi- 

 tions than are large seeds, which in themselves have a considerable 

 store of nourishment and for that reason may be planted deeper. 

 Clover is often sown on the surface, while peas and beans should 

 always be drilled in. Rolling the ground during dry weather, after 

 sowing the seed, is very important. In planting the nursery tree 



393 



