STATE POMOLOGICAL SOCIETY. 



103 



TABLE IV.— INFLUENCE OF COVER CROPS ON TREE GROWTH. 

 (YOUNG ORCHARD.) 

 (Average increase in trunk girth, first 5 years, in Expt. 333.) 



Cover Crop. 



Average 

 increase. 



Gain over 

 original girth. 



Rank. 



1 a 

 2b 



2 a 

 2b 

 3 



4a 

 4b 

 5 



6 

 7 

 8 

 9 

 10 



Medium red clover . . 

 Mammoth red clover 



Alsike 



Crimson clover 



Hairy vetch 



Cow peas 



Soy beans 



Oats and peas 



Rye 



Millet 



Rape 



Buckwheat 



Alfalfa 



Inches. 

 3.82 

 3.73 

 3.78 

 4.34 

 4.42 

 3.94 

 4.18 

 4.28 

 4.07 

 4.42 

 4.27 

 4.58 

 5.09 



Per cent. 

 183.65 

 192.28 

 204 . 32 

 245.40 

 245 . 56 

 175.11 

 201.94 

 235.16 

 233.91 

 238.92 

 239 . 89 

 237 . 30 

 306 . 63 



12 



11 



9 



3 



2 



13 



10 



7 



8 



5 



4 



6 



1 



Here again, it will be noted that the mulched and untilled 

 trees are distinctly superior to the others in their growth. Also, 

 it is shown that alfalfa can be safely and satisfactorily used, in 

 a young orchard at least, when its growth is prevented from 

 competing directly with the tree roots by means of a mulch. 



For use as a permanent cover and as a basis for a mulch, 

 alfalfa is thus shown to be very satisfactory. Its power of 

 nitrogen fixation and its perennial habit are much in its favor, 

 when used as stated above, but its strong affinity for moisture 

 and also for soil nitrogen would suggest caution in using it in 

 direct competition with the roots of the trees. More work is 

 needed on this point, however, and much more work is needed 

 on the relative values of various plants for permanent orchard- 

 covers and mulches, and on the best methods of handling them. 

 Almost nothing has been done along the latter line. Hairy 

 vetch, as noted above, has many of the qualities most needed 

 for this purpose, but definite and comparative data on it thus 

 far are lacking. 



Among the annual covers and those used along with tillage, 

 the best tree growth has been made in connection with hairy 

 vetch. This is not surprising when we remember that it fur- 

 nishes nitrogen and has a very low demand for moisture, — two 

 of the most important requisites for a plant to be associated 

 with trees. The surprising moderation of its moisture draft, 

 in comparison with other crops, can be seen readily in the fur- 

 row slice, when these plats are crossed with the plow. We 



