828 EXPERIMENT STATION RECORD. [Vol.35 



may be preferable to spring plowing. In 1915 cotton on disked corn ground 

 yielded at the rate of 696 lbs. of seed cotton per acre, while cotton on spring- 

 plowed corn ground yielded at the rate of 464 lbs. The average yield of seed 

 cotton per acre in a rotation where cotton was grown on disked corn land 

 from 1910 to 1915, inclusive, is reported as 661 lbs. as compared with 592 lbs. 

 in a rotation in which cotton was grown on spring-plowed corn land and 629 

 lbs. in the rotation where cotton was planted on corn l^nd plowed in August 

 of the preceding year. In 1915 subsoiling apparently decreased slightly the 

 yields of all crops, and for the period from 1910 to 1915, inclusive, the average 

 yields from all crops were also slightly less on land subsoiled than on land 

 not so treated. The use of manure gave more beneficial results on land used 

 continuously for the same crops than where crops were grown in rotation, 

 and it had a more favorable effect on the yields of cotton than on those of other 

 crops, but in none of the tests was the increased yield suCicient to justify the 

 expense of the treatment. 



Field peas planted in the fall of 1914 made a good growth during the vsanter 

 and produced a heavy crop for turning under in the spring. The quantity of 

 green material produced on the average of five plats was estimated at 10.6 

 tons per acre. On one plat the peas yielded at the rate of 2,888 lbs. of field- 

 cured hay per acre. In these experiments cotton yields have been less from 

 the plat where rye was used as a green manure than in similar rotations where 

 no green manuring was practiced. 



Growing a crop in alternate years with clean fallow between crops was not 

 found profitable in the production of corn, cotton, or oats for grain. The 

 method resulted in lowering the yields of both corn and cotton as compared 

 with the yields of these crops grown continuously on comparable plats. 



In studying the effect of rotation and tillage on root rot in cotton, it was 

 found that the disease is less serious in cotton grown in rotation with other 

 crops such as corn or oats than when grown continuously on the same land. 

 On a plat cropped continuously to cotton for seven years 25.7 per cent of the 

 plants died from root rot by the time the first picking was made in 1915, and 

 at the time of the second picking about six weeks later 49.7 per cent of the 

 total number of plants had died. The damage from root rot on this plat has 

 increased each year since 1912 when only about 1 per cent of the plants suc- 

 cumbed. On plats where cotton was grown on fall-plowed land in rotations, 

 including corn, sorghum, or oats, there was little or no root rot. Other results 

 secured indicated that the application of barnyard manure has a tendency to 

 check the spread of the disease. It was further observed that subsoiling ap- 

 peared to have a tendency to reduce the injury in cotton grown on spring- 

 plowed land, but it is not believed that this effect of subsoiling would offset 

 the cost of the work. 



In a variety test with corn the highest yield was made by Laguna, followed 

 by Brazos and Old Glory, both Laguna crosses. In a test of planting corn in 

 rows at different distances and of interplanting with cowpeas it was found 

 that where no cowpeas were planted between the rows the yield of corn rose 

 generally as the distance between the rows increased, the highest yield being 

 obtained where the rows were 7 ft. apart and with 4,078 plants per acre, and 

 the lowest where the rows were 4 ft. apart and with 4,480 plants per acre. 

 When the cowpeas were planted after the corn had a good start the growing 

 of a row of coviT)eas between the rows of corn did not lower the yield of corn. 



Cotton grown in rows 3, 4, 5, 6, and 7 ft. apart with the plants about 6 in. 

 apart in the row gave an average yield of seed cotton about 50 per cent 

 greater in the 7-foot rows than in the 3-foot rows. 



