EXPERIMENTS WITH FALLOW IN MONTANA 15 
The yields of oats and winter wheat after green-manure crops 
were approximately half those after fallow. The average yields after 
field peas as a green-manure crop were slightly more than those fol- 
lowing either winter rye or sweet clover as green manures. Yields 
immediately following green-manure crops were much less profitable 
than those from fallow. 
The yield of winter wheat has averaged about the same from fallow 
plowed in the fall and left rough the first winter as from that plowed in 
May. Fallow plowed in the fall and immediately cultivated gave 
lighter yields than that plowed in the fall and left rough the first 
winter. Fallow plowed in July showed consistently lighter yields 
than that plowed in May. 
Plowing 8 inches deep for fallow was more profitable with oats, 
barley, and winter wheat than plowing 4 inches deep or plowing 8 
inches and subsoiling to 18 inches. Subsoiling gave higher yields 
of oats than 8-inch plowing, but the increase in yield was not enough 
to pay the additional cost of preparation. Winterkilling made the 
results with winter wheat unsatisfactory. 
An application of barnyard manure before plowing for fallow has 
not increased the yield of either winter wheat or oats. 
For spring wheat the fallow period from harvest until the following 
seeding date is between 20 and 21 months. The total precipitation 
for this period varied from 11.60 to 20.46 inches. The water stored 
in the surface 3 feet of soil varied from 1.77 to 4.25 inches. The per- 
centage of the precipitation stored in the soil varied from 10.1 to 22.8. 
