78 THE CROWN-GALL AND HAIRY-ROOT OF THE APPLE TREE. 
fields. It had been planted to field crops for twenty years and had 
a clover crop when taken for the purposes of experiment. In the 
experiment on this plat 19,700 root grafts and trees were grown 
during 1903 and 1904 on 4 acres of land. 
Independent plat 2 consisted of about one-half acre of level land 
on the Potomac Flats, south of Washington, D. C. It consisted of 
an alluvial loam, the soil having been formerly pumped by dredgers 
from the bottom of the Potomac River. In this plat 6,400 root 
orafts and seedling trees were planted in 1907. 
Independent plat 3 consisted of about one-half acre of gently sloping 
clay loam on the Arlington Experimental Farm, in Virginia, south- 
west of Washington, D.C. In this plat 6,043 root grafts were planted 
in 1908. 
Cooperative nursery expervments——Experiments were conducted 
during the years 1905 to 1908 in cooperation with six of the largest 
nurseries in the Mississippi Valley. Eight experimental plats, of 
about 1 acre each, were planted in as many different localities in five 
States. <A total of 113,620 seedlings and root grafts was planted. 
A description of the plats follows: 
Cooperative plat 1 was located in southwestern Iowa on level valley 
land consisting of a colluvial clay loam. The previous crops for five 
years were grain. : 
Cooperative plat 2 was located in southwestern Iowa on sloping 
upland consisting of a light clay loam. The previous crops for five 
years were oats one year, corn one year, and plum trees three years. 
Cooperative plat 3 was located in southeastern Nebraska on level 
upland consisting of a loess loam. The previous crops for five years 
were corn one year and cherry trees four years. 
Cooperative plat 4 was located in western Illinois on level upland 
of heavy black loam mixed with clay. The previous crops for five 
years were grain. 
Cooperative plat 5 was located on level valley land in eastern 
Missouri consisting of a colluvial loam mixed with some sand. The 
previous crops for five years were cowpeas one year and peaches four 
years. 
Cooperative plat 6 was located in eastern Kansas on level valley 
land consisting of an alluvial sandy loam. The previous crops for 
five years were corn one year, osage ) orange one year, Kafir corn one 
year, and apples two years. 
Cooperative plat 7 was located in eastern Missouri on level valley 
land consisting of a colluvial clay loam. The previous crops for five 
years were cowpeas one year and peaches four years. 
Cooperative plat 8 was located in northwestern Arkansas on level 
valley land consisting of a sandy loam. The previous crops for five 
years were grain. 
186 
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