70 THE BOOK OF WHEAT 



of Hessian fly is imminent in a certain region, the farmers 

 should take concerted action for later sowing. Spring wheat 

 should usually be sown as soon as the ground is in a condition 

 for seeding. Winter wheat sown too late lacks the vitality 

 needed to withstand the cold, and sown too early it produces a 

 rank and succulent growth that is injured by freezing. 



The Depth of Seeding varies with the nature of the soil, the 

 amount of moisture, and the condition of the seedbed. In a 

 dry, sandy or cloddy soil, it is necessary to sow deeper than in 

 a wet, clay, or level soil. Ordinarily, the wheat should be 

 covered with about one inch of moist soil. 



Harrowing. After the ground is once plowed, the im- 

 plement most commonly used for further cultivation, either be- 

 fore or after sowing the wheat, is the harrow. There are three 

 principal objects in harrowing: (1) To kill weeds and grass, 

 which would otherwise absorb moisture and nourishment need- 

 ed by the wheat; (2) to level the surface and to keep it cov- 

 ered with a loose, dry mulch, both of which also conserve 

 moisture; and (3) to cover the seed. In drilled wheat the lat- 

 ter is performed in sowing. All three of these objects may 

 be attained in one operation. 



The most primitive method of harrowing was to drag over 

 the ground the limb of a tree with extending branches. This 

 implement, like the rude plow, is often found reappearing on 

 the frontier of civilization. It is easily improved and widened 

 by fastening together a number of branches so that it does 

 better work and covers a wider area. In California, in 1835, 

 the wheat was sown broadcast by hand and brushed in with the 

 branch of a tree drawn twice over the ground. The writer can 

 well remember when, as late as the middle eighties, he brushed 

 wheat into, the ground with a "drag" made from scraggy 

 wild plum trees cut on the banks of the Dakota river. A 

 similar implement was also used in other parts of the United 

 States. Another very primitive method of covering the grain 

 was that used in ancient Egypt, where it was trampled into the 

 loose ground by the hoofs of animals. 



The Romans used a kind of harrow before the Christian era. 

 In 1534 harrows with iron teeth were used in England, as 

 well as some with wooden teeth. In Northumberland, in 1650, 

 "the harrow was constructed without joints and without iron, 



