78 SOILS AND CROPS OF THE :^ARM. 



Summer fallowing, or plowing land in the spring 

 or fall and allowing it to lie during the summer, 

 either with or without further cultivation, is only ex- 

 ceptionally practiced in this country, and is not gener- 

 ally growing in favor. Where soils are badly infested 

 with weeds difficult to eradicate, or are especially com- 

 pact and tenacious, or have only a small supply of 

 available plant food, this practice may be advisable. 

 The condition of the soil may be improved; mineral 

 plant food may accumulate ; nitrogen will be absorbed 

 from the air and brought to the soil by rains, or by 

 the decay of vegetable matter. But, if the soil be 

 open textured, and if there be much rain, more nitro- 

 gen will be lost than is gained. There is the additional 

 great practical objection that the land makes no re- 

 turn in crop during the year. 



Few soils can be plowed when wet without injury. 

 Some sandy soils are little affected, but clay soils are 

 much injured by this practice. It is often almost 

 impossible to get a compact clay soil in good condition 

 after it has been plowed, or even much trampled by 

 live-stock when wet, until it has been exposed to the 

 actiunof frost. 



Harrowing. — Harrowing with any form of toothed 

 harrows affects the soil only to a moderate depth. 

 The operation is cheaply done. The same force 

 of men and teams may go over ten times as much 

 ground when harrowing as when plowing. It is a 

 good method of leveling the surface, helping pulverize 

 the clods, covering seeds, and of destroying weeds. 

 The best of the toothed harrows, however, only slowly 

 and imperfectly pulverize land where there are hard 

 clods, and have almost no effect at a greater depth 



