256 POWER AND THE PLOW 



the subsoil and the furrow slice, and the sod is then in condition 

 to rot with the greatest despatch. In from four to six weeks, 

 the land is plowed again, this time at a depth of four inches 

 or more. Disking and harrowing follow to prepare the seedbed 

 and form a dust mulch on the surface, thus conserving the 

 moisture for the following year's crop. The work of breaking 

 and "backsetting," as the second plowing is called, must be 

 done in the heat of the short northern summer. Daylight 

 lasts over all but a few hours of the twenty-four. Work presses, 

 but the severe toil of the horse must cease after eight hours, 

 ten at the outside. He must have food and rest when needed 

 most in the field. In this emergency, the traction engine 

 stands ready to do the work of two or three shifts of horses. 

 Not only does it do the work more cheaply, but, and this is 

 more important, it does it exactly at the right time. 



In the wornout lands of the nearer humid West, farmers 

 have found that summer fallowing, or resting and cultivating 

 the land a year between crops, gives new life to the soil. Scien- 

 tists tell us that the bacteria of the soil make available some 

 of the locked-up nitrogen, converting it into nitrates which 

 plants can assimilate. Wasteful methods have made this 

 necessary on some of the greatest wheat lands the world has 

 ever seen. Summer fallowing under humid conditions is a 

 confession of extravagance. In dry-land agriculture, it is 

 a periodical necessity. Referring to average prairie conditions, 

 the Minister of Agriculture for Saskatchewan stated, several 

 years ago, that "bare summer fallowing is becoming, and in- 

 deed in many parts had already become, the very foundation 

 upon which successful wheat culture is based and profitably 

 carried on. The practice of summer fallowing is usually 

 associated in the popular mind with the restoration of fertil- 

 ity; but not so in the West. Conservation of soil moisture 

 is the primary object of bare fallowing." 



In summer fallowing, two systems may be followed: either 

 to plow the land early after the weeds have once germinated, 



