13 
produced a larger yield than phosphate rock at the rate of 0.028 per 
cent P 2 5 . This indicates the more immediately effective influence 
of soluble phosphates. 
In view of the depressed growth of the preceding crop, it seemed 
imperative to make a second application of nitrogen and potash for 
the third millet crop in the same quantities as in the original formula. 
In this way it would be possible to measure further the cumulative 
effects of the phosphates and to determine if the decrease in growth 
was due to the exhaustion of available phosphate. The result of this 
test was a further decrease of growth, proving the removal of available 
phosphate. The effectiveness of phosphate rock was lowered con- 
siderably as compared with the previous crop. The influence of slags 
at this stage was the most important result on this crop. Other than 
the slags, the soluble phosphates were more effective than the insol- 
uble ones. 
After repeated failures to obtain a normal growth of turnips in the 
pots, due to insect attacks, experiment with this crop was abandoned. 
However, almost complete data for one series were obtained, and the 
results were very much in accord with the first crop of the millet 
series. Phosphate rock proved the least available, the other phos- 
phates were much more effective and very similar in their action. All 
applications had a markedly beneficial influence upon the growth of 
the turnips, and the plants to which lime was added were much* larger 
than those treated with lime and legumes. These pots were later 
planted to radishes, but through the ravages of insects and other 
causes the experiments with this plant were also abandoned. 
After standing for about nine months in the pots, the soil was well 
mixed and again seeded, this time to millet, in order to determine the 
relative availability of the phosphates after allowing ; tjie| soil.' to lie 
fallow. The results were rather surprising in that all potjs produced 
a very poor growth, but the pots fertilized with phosphorijc acid were 
in advance of the checks. When added at the rate of 0.007 per cent 
phosphoric acid, acid phosphate gave the highest yield, while phos- 
phate rock was second. When applied at the rate of 0.014 per cent, 
sodium phosphate was best, closely followed by the slags, phosphate 
rock, and acid phosphate in the order given. Since only a small per- 
centage of phosphoric acid could have been removed by the turnips, 
the stunted growth indicated the inability of the lime in the quantities 
added to retain the phosphates as calcium phosphate. 
The plants from the first two crops of millet and the crop of buck- 
wheat were analyzed, partly to determine the amount of phosphoric 
acid removed from the soil, and also to determine whether any relation 
existed between the types of phosphate used and the phosphate con- 
tent of the grain or straw. 
