242 



Journal of Agricultural Research 



Vol. m. No. 3 



similar manner, the results of the experiments as given in Table X are 

 averages for the six varieties. 



Table X. — Average oil content of six varieties of cotton seed grown for three seasons on 

 two different soil types at Thompsons Mills, Ga. 



Taking the average results for the three years, the red soil gave only 

 slightly heavier seed, with a somewhat smaller proportion of hulls than 

 the gray soil, and there was practically no difference in the oil content. 

 Each year the seed was heavier and contained a smaller proportion of 

 hulls on the red soil than on the light soil, but the case is quite different 

 as regards the oil content. In 1909 the oil content was considerably 

 higher on the red soil than on the gray, while in 1910 these relations were 

 reversed and in 191 1 the differences practically disappeared. In other 

 words, the comparative effects of the two soil types depend on the seasonal 

 conditions, and it so happened that there was a balancing effect for the 

 three years covered by the experiment. 



Extensive data have been accumulated as to the effect of soil type on 

 the oil content of soy beans, but these data are too voluminous to present 

 in detail, and only a summary of the results can be given here. In 191 1 

 plantings of six varieties of soy beans were made on the two above-men- 

 tioned soil types at Thompsons Mills, Ga. , and data were secured as to the 

 relative oil content of the beans. The data given in Table XI are the 

 averages of three plantings, made on May 6, June 3, and June 21, re- 

 spectively, for the six varieties designated as S. P. I. Nos. 17254, 17263, 

 17857, 18227, 19984. and 20892. In 1912 five varieties were grown on a 

 heavy clay soil at the Arlington Experiment Farm and on an infertile 

 sandy soil containing a large percentage of coarse sand. The latter soil 

 is composed largely of material dredged from the Potomac River and is 

 designated as Potomac Flats soil. These two soils are only about half 

 a mile apart, so that the weather conditions during the growing season 

 were essentially the same. While, as stated, five varieties were used in 

 this experiment, data for only two of these, S. P. I. Nos. 30599 and 30745, 

 as a basis for comparison with the greenhouse experiment next described, 

 are given in Table XI. 



