Accumulation of Nitrogen 



115 



very useful. The reader must also be reminded that much 

 of the value of the cover-crop depends on its being plowed 

 under very early in spring (Fig. 23). 



It is probably not often that one secures too rapid 

 growth of his fruit-plants by the use of leguminous cover- 

 crops, and yet it seems to be a common opinion among 

 growers that this may occur. The experience of George 

 T. Powell, in eastern New York, has been much quoted. 

 In a pear orchard he grew three very heavy successive 

 crops of crimson clover and plowed them under, with 

 the result that the trees grew too heavily and bore 

 too little. An analysis of the soil was made by Cava- 

 naugh and also of the same character of soil from a 

 neighbor's field just across the fence, with the following 

 results: 



Three crops 



crimson clover 



Per cent 



No clover 

 Per cent 



Water 



Nitrogen 



Humus 



Phosphoric acid (available) 



15.00 

 .21 

 2.94 

 .016 



8.75 

 .12 



1.91 

 .008 



These percentages are calculated to the acre, estimating 

 1,500,000 pounds of fine soil to the acre-foot (3,000,000 

 pounds is the average weight of an acre-foot, but in this 

 case about 50 per cent of the soil was sufficiently fine 

 to be included in the analysis); the increase in per- 

 centages, as computed to pounds or tons to the acre, 

 is as follows: 



Water 6.25 per~cent=46.875 tons to the acre. 



Nitrogen 09 per cent=l,350 pounds to the acre. 



Phosphoric acid. . .007 per cent= 105 pounds to the acre. 



