. 
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2 BULLETIN 1478, U. S. DEPARTMENT OF AGRICULTURE 
slightly more than 2 inches between plants. This unusually close 
spacing produced more cotton than wider spacings, even though the 
season was very dry. 
The results of 18 separate tests during this 5-year period show that 
yields are more likely to be reduced than increased by chopping. 
GENERAL CONDITIONS AT GREENVILLE 
The United States Cotton-Breeding Field Station at Greenville, 
Tex., is an outgrowth of work conducted since 1904 in Texas and 
adjacent States by the Office of Cotton, Rubber, and Other Tropical 
Plants, of the Bureau of Plant Industry, United States Department 
of Agriculture. The station was established in 1918 through a coopera- 
tive agreement between the department and the Greenville Chamber. 
of Commerce. It consists of a 60-acre tract of typical black land 
about 4 miles southwest of Greenville. 
Greenville is situated in Hunt County, in northeastern Texas, about 
52 miles northeast of Dallas and 60 miles southeast of Denison. It 
is on the line of division between the well-known black-land prairie 
belt and the interior coastal-plains country of the eastern part of the 
State. The black-land belt forms the principal cotton-growing sec- 
tion of the State, while the interior coastal-plains area includes a 
large part of the sandy soils characteristic of eastern Texas. The 
black-land or black ‘‘ waxy” soil is technically described as Houston 
clay. Itis avery heavy, fertile clay, highly retentive of moisture, 
which enables plants to remain in a growing condition over long 
periods of dry weather. 
The 10-year average annual precipitation is 39.09 inches. The 
growing season is approximately 235 days, with the first killing frost, 
over a 10-year average, on November 11, and the last in the spring on 
March 21. Though occasional wide departures from these means 
may be expected, the greatest climatic variation is with respect to 
rainfall. 3 
EXPERIMENTAL METHODS 
The experimental lots of cotton were planted, thinned, and picked, 
so as to provide several side-by-side comparisons of the different 
spacings. ‘These comparisons were made on the basis of alternating 
4-row blocks. Where a greater number of comparisons are provided 
for, an opportunity is given to study in greater detail the consistency 
of behavior, and the effect of soil variation is lessened. Some of the 
first experiments discussed do not provide an adequate number of 
comparisons to be handled satisfactorily on a statistical basis, but 
they are indicative in conjunction with other experiments. 
The Lone Star variety, of the Texas big-boll storm-proof type of 
cotton, was planted in all of these experiments, and the rows were 
usually spaced 40 inches apart. With few exceptions, thinning was 
done when the plants were about 6 inches high and were bearing 
from five to seven true leaves. Unless otherwise indicated, thinning 
was done by hand, the plants being left at measured distances, as 
near as the stand would permit. 
Flower counts were made daily on the two inside rows oi each 
block, from the appearance of the first flower until the peak of flow- 
ering had been passed. 
At picking time the experiments were divided into sections by 
stretching strings across the rows at accurately measured distances, 
