IT. S. DEPARTMENT OF AGRICULTURE. 
Under the subhead " Green manured" are given the yields of wheat 
following the plowing under of rye, peas, or sweet clover, as speci- 
fied. This treatment is in 4-year rotations in which one of the other 
crops is corn and the other is one of small grain. 
At each station several plats of spring wheat are grown on sum- 
mer-tilled land. One of these is from land alternately summer 
tilled and cropped to wheat; one is from a 3-year rotation of summer 
tillage, wheat, and oats; and others are from 4-year rotations in 
which the other crops are corn or potatoes and oats or barley. 
The method of summer tillage practiced has been of the intensive 
type. The ground is fall plowed and clean cultivation is continued 
through the next year and until the wheat is seeded in the second 
spring. In some cases it is necessary in order to destroy weeds to 
replow during the summer when the land is fallow. At other sta- 
tions summer-tilled plats are plowed but once. Experiments not 
here reported are under way to ascertain the best method of fallowing. 
Indications are that equally good results can be obtained with a less 
intensive method than has been practiced in the investigations here 
reported. 
The yields given in these tables begin with the second year of crop 
production at each station. All crops are produced the first year on 
land uniform in its treatment. In some cases an entire crop has 
been lost by hail. These years are not considered in computing 
averages, as the crops resulting from all methods alike were destroyed. 
By the use of the basic data which follows in Tables II, III, and 
IV there has been compiled a second part embodying a summarized 
statement of the table of yields for each station. In this summary 
are brought together in different form the yields in the first part of 
such table. The value of the average yields thus obtained is shown 
together with the cost of production (as computed from the avail- 
able data). In the last line of the table is given the average profit 
or loss resulting from the production of wheat by the method shown 
at the head of the column. Loss is indicated by the minus sign. 
COMPARISON OF CULTURAL METHODS ON THE BASIS OF COST. 
In order to make a comparison of the relative profits or losses of 
the several cultural methods, as shown in the second part of the 
table for each station, it was necessary to establish the average cost 
of production under each of these methods. The methods under 
study vary a great deal in the labor involved and in the consequent 
cost of preparation. Table IV has therefore been compiled in order 
to show the average cost of the methods under study as determined 
from the data of eight of the stations having the most trustworthy 
records. An average of the records for 5| years at each station has 
