634 Agricultural Experiment Station, Ithaca, N. Y. 



mented largely in raising wheat continiiouslj on the same ground. 

 Like experiments have also been conducted at Cornell University. 

 Six crops of wheat have been taken consecutively and seven of corn 

 without an intervening crop. In the first instance, no grass or 

 fertilizers of any kind were used. In the second, the field was 

 treated to five tons of farm manures yearly. In all of these cases, 

 there were no indications that the plants had exuded anything from 

 their roots which was deleterious to subsequent plants of the same 

 species, neither were there any indications that under superior 

 culture, with or without fertilizers, reasonable success might not be 

 secured without rotation. Of course it is well understood by the 

 thoughtful investigator that there is usually great economy in rota- 

 tion for various reasons which it is not necessary to state here. 



Two reasons have been assigned for the failure to successfully 

 raise nursery stock continuously on the same land. The first is,, 

 that the plants have exhausted all the readily available plant food, 

 and since nursery stock, to be at its best, must have an early and 

 rapid growth, it is impossible without weathering the land and 

 allowing some of the plant food in the subsoil to rise to the surface 

 to secure satisfactory results. It should be kept in mind in this, 

 connection, that under proper culture and conditions in dry weather, 

 plant food rises from the subsoil to near the surface, while in very 

 wet weather it may pass from the surface downward. Nursery 

 trees get a large percentage of their nourishment from the subsoil, 

 and during the two to five years that the ground is occupied by 

 them, a portion of the available plant food in the subsoil is used. 

 This would explain in part the difficulty of using land continuously 

 for growing young trees. 



Another reason has been assigned for the fact : nursery lands in 

 trees are not always cultivated when the soil is in the best condition. 

 So much is always to be done in the spring of the year, that the 

 intervals between the rows are often plowed when the land is too 

 wet or too dry. Again, the digging of the trees is usually performed 

 late in the fall or early in the spring when the soil is little better 

 than a mortar bed. The digging and trampling, especially on clay 

 soils, when the land is in this condition, puddles it, and the larger 

 part of the available plant food is locked up, and it requires one or 

 two years of culture and even manuring to bring the land back to 

 its normal condition. But all these explanations do not fully account 

 for the imperfect [growth of the second crop of trees, for after 



