340 BuLLF/riN 82 



It was also deemed advisable to attempt the control of Johnson 

 grass by reducing the vitality of the rootstocks by exposing them to 

 intense sunlight, sun-heat, and aridity. It appeared desirable to sup- 

 plement this method with more or less cultivation. 



In carrying out the above plan six fields were laid out: 



Field C, a 40-acre tract, was set aside to be held fallow from 

 the time of removal of a wheat crop in June, 1915, until December, 

 1916, at which time another grain crop was to be planted. After the 

 removal of the second crop, when the land was sufficiently freed from 

 Johnson grass, it was planned to seed it to alfalfa. 



Field D, containing 20 acres, had been in sorghums for a number of 

 years until November, 1915, when it was plowed and seeded to barley. 

 After the removal of the barley crop plans were made to pasture the 

 field with sheep until such time as the Johnson grass should be under 

 perfect control. 



Fields E and F, each containing 10 acres, were set aside for the use 

 of summer crops which demanded considerable cultivation. The crops 

 chosen were Egyptian cotton and dent corn, to be alternated each year. 



Field G, containing 20 acres, was to be dry fallowed during the 

 summers and planted to grains during the winters. 



Field H also contained 20 acres on which a continuous dry fallow 

 was to be maintained until the experiment should close. 



OPERATIONS IN DETAIL 



FIELD C; SUMMER FALLOW, WINTER GRAIN 



Following the removal of wheat in June. 1915, Field C was kept 

 dry and plowed during the following August, being left rough through- 

 out the succeeding winter. Early in the spring of 1916 there was a 

 luxuriant growth of volunteer grains. The summer plowing of the 

 previous year had very greatly reduced the vitality of the Johnson 

 srass rootstocks and almost all of the weed that was evident in the 

 spring of 1916 was a seedling growth which had been germinated by 

 the winter rains just preceding. To prevent these seedlings from 

 attaining sufficient maturity to send out new rootstocks the land was 

 again plowed in April, 1916. Summer rains caused the germination 

 of still more seed and a third plowing was made in August, 1916, prior 

 to seeding small grains in December. At the time of seeding virtually 

 no old Johnson grass plants with appreciable vitality were noted. The 

 small grains planted at this time were harvested in June, 1917, and 

 the land was left dry until August at which time it was plowed prior 

 to seeding to alfalfa in November. By the time of this last plowing 



