12 BULLETllSr 402, U. S. DEPARTMENT OF AGRICXJLTTJRE. 



Throughout the period of the test it has been necessary to sub- 

 divide the tenth-acre units in at least a portion of the series in order 

 to make sufficient divisions for all of the work being done. The 

 subdivisions have usually been twentieth-acre plats, formed by 

 making a 16-inch alley between the subdivisions and reducing the 

 width of the alley between tenth-acre plats. Smaller plats are used 

 when sufficient seed is not available to sow the standard plat. 

 Usually no plats smaller than 0.01 acre in size are classed as field 

 plats, but in a few instances plats containing 0.008 acre have been 

 called field plats. Nursery rows have been used for the prehminary 

 tests, and many varieties tested in the nursery have proved so poorly 

 adapted to conditions that they were never grown in the field plats- 

 Careful agronomic and physiologic observations have been made and 

 are preserved in the form of annual reports. 



REPLICATION OF PLATS. 



Until 1915 only one plat of each variety was grown each year, 

 but a leading variety of each cereal was used as a check. Usually 

 there were five or more check plats from which the data could be 

 averaged. In 1915 aU of the leading varieties were sown in dupli- 

 cate twentieth-acre plats. The value of repeating aU. the varieties 

 in the experiment is apparent, and more extensive repfication is 

 planned for the future. 



SOIL TREATMENT. 



In preparing the land for experimental tests the aim has been to 

 conform as closely to farm practice as possible. The plowing has 

 been done at the moderate depth of 5 to 7 inches, and subsequent 

 treatment has been in accord with common farm practice. The 

 cultivation has been limited to that required to control weed growth. 



Most of the experimental work has been conducted on land summer- 

 fallowed the previous year. This was done to keep the land uniform 

 and to assist in the control of weed growth. When the experiments 

 were begun, summer fallowing was thought to be the most profitable 

 method of production. In 1914 the spring-wheat varieties were 

 grown on land which had been cropped to com the previous year. 

 Oats have been grown following potatoes or fallow. 



The usual practice in summer fallowing has been to plow in the 

 spring and pack with the disk harrow. Weeds were kept in check 

 during the summer by two or three subsequent diskings. Usually 

 the last treatment immediately preceded the sowing of the grain, 

 either in the fall or the spring. 



Rate-of-seeding and date^of-seeding tests were included in the 

 same series of plats as the varietal work and were on land receiving 

 the same soil treatment. 



