26 BULLETIN 218, U. S. DEPARTMENT OF AGRICULTURE. 
Subsoiling and listing show small increases over similar stubble 
fall plowed. 
The shortness of the record and the inconsistency among the yields 
make it unsafe to base conclusions on such small differences. 
When cost of production is considered in connection with yields it 
is seen that the only things that stand clearly by themselves are 
disked corn ground, with an average profit of $3.39 per acre, and the 
use of green manure, with a loss of $5.75. The other methods as 
grouped here show either losses or gains so small as to be subject to 
changes in their relative positions by a single crop. 
NORTH PLATTE FIELD STATION. 
The work here presented is conducted on the table-land of the 
North Platte Field Station. The soil is of the type generally known 
as loess. With the exception of the humus accumulated near the 
surface, it is practically uniform to great depths. The storage and 
use of water is unlimited by the depth of the soil or any peculiarities 
in it. The development of roots is limited only by the physiological 
character of the crops grown and the available moisture. It is a 
soil on which a maximum of results from tillage methods would be 
expected. 
The North Platte Field Station presents for study the records of 
eight years. In three of these years the production has been good, 
in three it has been poor, and in two years the crop has been a 
failure. 
Spring-plowed wheat stubble has given better results than fall 
plowing hi five of the six years that have produced crops, but the 
great difference in favor of fall plowing hi 1908 reduces the average 
gain from spring plowing to less than 2 bushels per acre. 
On the plats continuously cropped to oats fall plowing has given 
better results than spring plowing in four of the six years, the average 
advantage in favor of it being more than 4 bushels per acre. The 
spring-plowed plat following oats is the only one in the series that 
is given shallow plowing. 
Fall plowing oats after oats has been consistently better than after 
wheat, while with spring plowing the reverse has been the case. 
The poorest yields have been obtained following alfalfa and brome- 
grass. These two crops exhaust the available soil moisture and leave 
the following crop entirely dependent upon seasonal rainfall. Oats 
following them have usually been the first to suffer from drought. 
Disked corn ground shows about the same average yields of oats 
as the crop raised after small grains. 
Oats following green manure show a small increase in average 
yields over all other methods except that of summer tillage. Little 
