MAINTAINING FERTILITY 41 
receive a dressing of manure once a year. In addi- 
tion to this, the summer crops especially should be 
well supplied with phosphoric acid and potash. 
At the New Jersey Station, nine acres were 
devoted to the growing of soiling crops, during a 
period of nine years, crops succeeding each other 
immediately, and the soil, instead of becoming 
less fertile, increased in productiveness, notwith- 
standing the continuous drain on the land and actual 
removal of large quantities of fertility constituents. 
This was undoubtedly due to extra cultivation, to 
manure applied once each year, to commercial 
fertilizers applied with the other crops, and to the 
further fact that the land was covered with some 
crop in winter. This practice of cover-cropping 
not only provided abundance of fdod, but prevented 
losses of constituents, as the land was not left bare 
in fall and winter. 
PREPARATION OF LAND 
In the growing of soiling crops under intensive 
systems, it is better, as a rule, to plow but once a 
year, preferably in spring. In the preparation of 
land for the other crops, it is advisable to use a 
cutaway harrow, thoroughly pulverizing the soil 
at a depth of three to four inches. The advantages 
of this method are that the cultivation conserves 
moisture should the weather be dry; while the 
