I20 AGRICULTURE OF MAINE. 



sulphur as a fertilizer may become a common agricultural 

 practice. As a matter of fact sulphur is a constituent of cer- 

 tain of the compounds ordinarily used in commercial fertilizers 

 s.uch as potassium and ammonium sulphates. 



We are apt to regard the soil simply as a storehouse for 

 plant food materials but we lose sight of the fact that much of 

 this food material is not in condition for the plant to take 

 hold of it. It is, as we say, unavailable. How does it become 

 available? Through the activities of millions uf>on millions of 

 minute living organisms. What do these organisms do ? Under 

 favorable conditions they are constantly at work tearing down 

 the more complex organic substances such as those which make 

 up the tissues of the cover crop which is plowed under in the 

 spring, or the stable dressing which is applied, or any other 

 animal or vegetable substance in the soil, and converting what 

 otherwise would be absolutely useless to the plant into more 

 simple chemical compounds which it may readily absorb through 

 its roots. What are favorable conditions for their work? The 

 presence of an adequate supply of moisture, food, air and 

 warmth and an alkaline condition of the soil. How are these 

 conditions best supplied ? By cultivation and increasing the 

 humus content of the soil by plowing under cover crops and the 

 application of stable dressing or other fertilizer and liming 

 where necessary. 



Thus we have seen that the soil of the orchard is not only a 

 storehouse for plant food materials but that it is a vast manu- 

 factory filled with tiny machines, each working day and night 

 when conditions are favorable, turning out a product which the 

 tree can use to build up into food for its tissues. These pro- 

 cesses go on most actively in the spring and early summer. The 

 cover crop which served its purpose the fall before in checking 

 too long continued growth and the production of immature 

 wood, prevented washing by fall rains, and helped to protect 

 the roots from the rigors of winter. It also stored up in its 

 tissues some of the available food materials of the season 

 before which would have been washed away and lost. When 

 turned under in the spring it at once furnishes food for these 

 beneficial soil bacteria to grow upon and multiply and to con- 

 vert into substances which may be used by the trees. It tends 

 to lighted the soil, and to admit the air which is also essential 



