SPBING WHEAT JX THE CHEAT PLAINS AREA. 43 
(4) Some soils, even in the regions of profitable spring-wheat pro- 
duction, show little response to cultural methods. 
(5) Reducing the cost of production has in most cases in these 
investigations proved a more important factor in determining profits 
than increasing yields by cultural methods. 
(6) Northern Colorado and Kansas seem from these investigations 
to be the southern limit of profitable spring-wheat production on 
the Great Plains. Tins limitation does not apply to winter wheat 
and other crops under investigation. 
(7) Disked corn ground has given consistently high yields. This, 
together with the low. cost of preparation, has resulted in its showing 
the highest average profit or lowest average loss of any of the methods 
tried at all of the fourteen stations except one. These profits are based 
on the assumption that the corn crop was so. utilized as to pay for 
the cost of its production. (If the corn crop was grown at a loss, 
this loss should be deducted from the profits on the wheat crop 
folio whig it.) 
(8) Furrowing with a lister and leaving the surface ridged through 
the winter has resulted in a small increase in yield over plowing at 
seven of the eight stations where it has been tried. As it is a some- 
what cheaper method of preparation than plowing, it has conse- 
quently been more profitable. 
(9) The average difference in the yields of spring wheat following 
fall plowing and spring plowing are very small. At most stations 
the advantage of one over the other depends upon the season. 
(10) Subsoiling has been of doubtful utility as a means of increas- 
ing yields. As a means of overcoming drought it is without value. 
(11) Summer tillage without crop has given the highest average 
yields of any method under trial at 12 of the 14 stations. However, 
on account of its high cost, due to extra labor and alternate-year 
cropping, it has not been the most profitable practice. 
(12) The most expensive method under trial is green manuring. 
It has produced less profit or greater loss than any other method 
under investigation. 
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