FIELD CROPS 451 



r As a general rule wheat is sown thicker-on poor soils, stiff and cold 

 clay lands, and rough and cloddy seed beds than on fertile soils, 

 friable loams, and fields well worked and smoothed before seeding. 

 Late sowing and broadcasting also require more seed than early 

 sowing and drilling. A large-grained variety requires a greater 

 quantity of seed than a fine-grained sort, and a variety with limited 

 stooling capacity more than a heavy stooling variety. Generally 

 the quantity of seed per acre varies from 6 to 8 pecks, but in dry- 

 land farming as a rule less is used. 



There are two common methods of sowing wheat, viz., drilling 

 and broadcasting. Different kinds of machines are used for both 

 operations, but broadcasting is also done by hand. Drilling is done 

 with common drills, press drills, shoe-ana-chain drills, disk drills, 

 etc. Each method has its advantages under certain conditions. The 

 results at most of the experiment stations are in favor of drilling. 



Rolling and sometimes harrowing is resorted to during the 

 early stages of the crop. Late rolling and late harrowing are often 

 injurious. In dry climates and seasons cultivation between the 

 drills is sometimes carried on. 



Crop Rotations. The pl-vc of wheat in the crop rotation ia 

 largely governed by the cleanness of the soil, the adaptability of 

 wheat as a nurse crop for clover and grass, the possibility of either 

 fall or spring sowing, the comparatively early ripening of the crop, 

 the fertility of the soil, and other conditions. 



Hoed crops and summer fallow, especially if cultivated, tend to 

 leave a greater quantity of water in the soil than growing broad- 

 casted and uncultivated crops, such as the small grains. In a dry 

 season, for this reason, wheat after corn or cultivated summer fallow 

 is likely to give a much better yield than if grown after wheat 

 or oats. On some new soils wheat is sometimes grown for several, 

 years in succession on the same land, but continuous cropping ex- 

 "periments have shown that after a series of years the yields begin 

 to decline, and rotation experiments have clearly indicated that 

 better yields are obtained from soils under rotation than those 

 growing wheat year after year. 



Irrigation and Rainfall. Successful wheat culture does not 

 depend so much upon the total annual rainfall as it does upon the 

 amount of moisture the soil furnishes the crop during the growing 

 period. The total rainfall in some of the wheat-growing localities 

 of the West and Northwest ranges annually from 12 to 18 inches, 

 which falls mainly during the winter, and yet good crops are pro- 

 duced without irrigation, while in other sections the same amount of 

 rainfall is insufficient for a profitable yield. Again, in many humid 

 regions which have a yearly precipitation of as high as 40 inches, 

 the water runs off in the drainage, and less than half of the total 

 precipitation is available to the growing plants. The question, there- 

 fore, is not alone how much rainfall there is, but how much of it 

 is retained by the soil for the use of the crop. The relation of rain- 

 fall to wheat culture is largely a question of soil conditions. It is 

 a significant fact that a very large proportion of the wheat of the 



