WHEAT 125 



bined harvester, and the quite general introduc- 

 tion of the practice of summer-fallowing the land. 



"The development of the combined harvester 

 has, without doubt, decreased the cost of pro- 

 duction where grain is grown upon a large scale, 

 but it has at the same time tended to encour- 

 age a desultory system of culture, and rendered 

 the fields very foul through a general distribution 

 of weed seeds, because by the time the grain is 

 harvested in this manner practically all the serious 

 weeds have fully ripened their seed; and further, 

 the length of time the grain is left in the field 

 after maturity has tended to seriously increase 

 the loss from shattering by the wind. It is very 

 questionable, then, whether the combined effects 

 of these undesirable factors have not more than 

 offset the decreased cost. 



"The summer fallow (summer tillage) practice 

 was introduced for two reasons; first, it was an 

 attempt to save as much of two season's precipita- 

 tion as possible for the production of a single 

 larger crop; second, to clean the land of weeds 

 resulting from continued grain culture. The latter 

 effect has been largely offset by the use of the com- 

 bined harvester. 



"The shallow preparation of land and the con- 

 tinual practice of burning off the straw have had 

 a very bad effect upon the humus content of 

 the top foot of the soil, which in turn has so 

 affected its physical condition, generally speaking, 

 as to materially reduce its moisture capacity and 

 seriously affect the yield of grain. Further, the 

 earlier seeding made possible by the summer 



