SPRING WHEAT IN THE GEEAT PLAINS AREA. 7 



the calculation is from the left. For a rough comparison of seasons, 

 the bottom line of the first half of the table gives an average of all 

 plats for each year, the average of the yearly average yields appear- 

 ing in the last column to the right. 



Throughout the tables, where wheat is shown as following corn 

 on either fall or spring plowing, it is in a 3-year rotation in which 

 the other crop is oats. Where wheat is shown as following oats 

 on fall or spring plowing, it is in a 3-year rotation where in the third 

 year the land is either cropped to corn or is summer tilled. Where 

 wheat follows wheat under any treatment it is in a system of con- 

 tinuous cropping to wheat by the method indicated. 



The methods of operation have been similar at all stations. Fall 

 plowing is done early, except after crops like corn that are not 

 removed from the ground early. It is done to a good depth, the 

 standard being set at 8 inches. Ground may be either worked down 

 or left rough over winter. Spring-plowed land may be disked in the 

 fall or may be undisturbed until spring, when plowing is done just 

 before seeding. Plowing is done to a good depth, usually at about 

 8 inches. This applies to all wheat plats except one plat at each 

 station on which wheat follows wheat. The stubble of this plat is 

 undisturbed until spring, when it is plowed shallow (at about 4 

 inches) and is then given a minimum of cultivation, which usually 

 consists of one or two harrowings. In those cases where an addi- 

 tional plat appears under spring plowing after wheat, it is plowed 

 deep instead of shallow. 



Under the subhead " Listed" there is shown at some stations the 

 yield from one plat continuously cropped to wheat. Instead of 

 plowing this plat, it is furrowed out with a lister at the time of fall 

 plowing. It is cultivated down level by seeding time. 



Under the subhead u Subsoiled" there is shown at the stations 

 where it has been tried the results from a plat continuously cropped 

 to wheat. At the time of plowing, a subsoil plow is run in the bot- 

 tom of the furrow, usually loosening the soil to a total depth of about 

 14 inches. The variation from this depth is hardly more than 2 

 inches either way. In general, subsoiling has been done two years 

 in succession and then omitted for two years. 



Under the subhead "Disked" is given the average of a consider- 

 able number of plats of wheat following corn. These occur in alter- 

 nate cropping to wheat and corn, in 3-year rotations in which the 

 other crop is oats, and in 4-year rotations in which the other crops 

 are summer tillage and oats or barley. In sod rotations, wheat on 

 disked corn ground is the third crop after breaking the sod. At 

 some stations are shown additional plats on disked ground following 

 potatoes and following sorghum. These are in 4-year rotations. 

 85751°— Brill. 214—15 2 



