332 CONNECTICUT EXPERIMENT STATION REPORT,, IQOO. 



the leaves. These leaves, as well as much of the grass growing 

 under the trees, are crops which have been gathered annually 

 for more than a century from our streets and parks; a crop 

 which is rich in mineral matter and hence impoverishes the soil 

 on which it grows, as our field and garden crops exhaust the 

 fertility of land. Just as no market gardener thinks of success 

 in farming without a yearly dressing of the land with fertilizers 

 of some sort, so in our city parks the best success with trees 

 cannot be expected on a soil which has supported their life for 

 more than a hundred years, unless the supply of plant food in 

 the soil is supplemented by the use of fertilizers. 



The soil is further exhausted by the removal of a part of the 

 grass whenever it is cut in our parks. 



It is true that trees have the power to gather food enough 

 to support life and make some growth even from soils which 

 are, agriculturally speaking, almost barren. It is also true 

 that the wastes of the community which pass into the soil help 

 to feed the trees standing upon it. Moreover, from time to 

 time, some fertilizing material has been put on our public 

 squares with the object of improving the grass. But these 

 various things do not fully meet the requirements of the trees. 

 The yearly application of some suitable fertilizer to the soil 

 about shade trees, is of the highest importance to increase their 

 growth and what is more vital their thrift and their power 

 of resisting unfavorable conditions. 



4. Mutilations of Trees. 



A very large number of the trees on the streets of New 

 Haven, not only such as are newly planted, but also those of 

 the larger sizes, have been and are now being injured and even 

 ruined by the gnawing of horses, which contrary to city ordi- 

 nances are hitched to them or left unhitched to bite and tear 

 the tree trunks. 



The damage done in this way is well shown in figures I 

 and 2 of Plate VIII following page 338. 



To show the extent of damage by horses, the following 

 statement, based on personal observation, gives the total number 

 of trees on the streets named, the number of such trees damaged 

 by the gnawing of horses and collisions of vehicles, and the 

 percentage of mutilated trees. 



