330 EXPERIMENT STATION RECORD. 



relative .solubility of the constituents of virgin soil, old tield soil, and 

 subsoil in carbonated water (saturated with carbon dioxid under a 

 pressure of two atmospheres). The averages of 33 determinations in 

 each case showed the greatest solubility in case of the virgin soil and 

 least in case of the subsoil. The variable character of the carbonated 

 water and its low solvent power for phosphates are considered insuper- 

 able objections to its use for this purpose. The author recommended 

 one-fifth normal nitric acid, and reported comparative studies of the 

 solubility in this acid of the potash, phosphoric acid, and lime of good 

 and poor tobacco soils and of pasture soil, as well as of the first two 

 in hydrochloric acid of 1.115 sp. gr. The results showed a small 

 percentage of available potash, but very large amounts of available 

 phosphoric acid and lime, in all soils and to all depths down to 2 feet. 

 Incidentally it was found that the poor tobacco soil was much richer 

 in nitrates than the better soil. Methods of sampling soils were 

 briefly discussed, and the concentrating of attention on the first 6 

 inches of soil as that part of most importance in plant production was 

 advised. 



Director C. E. Thorne presented a paper on Soil Investigation, in 

 which he pointed out the necessity of supplementing chemical analysis 

 and pot experiments with carefully conducted field experiments, and 

 also' of giving more attention to the biological processes in the soil. 

 The results of a 7- year rotation with corn, oats, and wheat, and of a 

 3-}^ear experiment with clover, at the Ohio Station, using lime and 

 various fertilizer combinations, were reviewed, showing that phos- 

 phoric acid is apparently the first requirement of cereals on the soils 

 experimented with, and lime the first requirement of clover, potash 

 being second in importance for this crop. The beneficial effect of the 

 lime, particularly on the clover crop, was apparently due to the acid 

 condition of the soil, the character of the growth of the clover being 

 a reliable index of the acidity and the need of lime. Such acid soils 

 were shown to be widely distributed in Ohio. 



Attention was called to the fact that the action of certain forms of 

 nitrogen, particularly ammonium sulphate, on acid soils is greatly 

 improved by applications of lime. It was also noted that plants vary- 

 with reference to sensitiveness to soil acidity, wheat being especially 

 resistant. While the source and nature of the soil acids are not well 

 understood, there are indications that they may be, in part at least, 

 the result of biological processes. 



Discussing this paper, Dr. J. G. Lipman urged the importance of 

 more careful study of the relation of acidity to bacterial activity on 

 the one hand and to the physiological processes of the plant on the 

 other, especially as affecting the solubility of the nitrogen compounds 

 present in the soil or diffused from the cells of the plant roots or the 

 root tubercles. 



