38 
The results in Table XIV show that when guanos remain six weeks 
in the soil, the availability of the phosphoric acid is slightly depressed, 
in others slightly increased, and in most guanos very little affected. 
The availability of bone meal and floats was quite markedly increased 
by remaining in the clay and very little depressed in the sand. 
In the red clay the favorable or unfavorable effect of remaining 
in the soil was more marked than in the sand. 
Liming the red clay tended to diminish the increase or decrease in 
availability produced by remaining in the soil. 
Efficiency of the phosphoric acid as affected by liming. — It has been 
shown by Prianishnikov * and Wheeler 2 that the efficiencies of many 
phosphates are notably affected by liming, while others are only 
slightly affected. Obviously the degree to which availabilities are 
affected depends somewhat on the nature of the soil and the length 
of time the phosphates remain in the soil before they are assimilated 
by the crop. 
To gain some idea of how bat guanos are affected by liming, the 
efficiencies of bone meal, floats, slag, and 11 guanos were compared 
with those of acid phosphate in limed and unlimed red clay and river 
sand. Detailed results of the tests are given in Tables XIII and XV, 
a summary of the results in Table XVI. 
For the test in Table XV, millet plants were grown 30 to the pot 
in river sand No. 213 (41 pounds dry soil per pot with a water con- 
tent of 18 per cent). The crop was produced from August 17 to 
September 29, 1916, with a basic fertilizer consisting of 8.4 grams 
sodium nitrate, 6 grams ammonium sulphate, and 8 grams potassium 
sulphate per pot given in two applications. 
i Prianishnikov, D. tjber den Einfluss von kohlensaurem Kalk auf die Wirkung von verschiedenen 
Phosphaten. Landw. Vers. Stat., 75 (1911), No. 5-6, pp. 357-376. 
8 Wheeler, H. J. After-effects of certain phospates on limed and unlimed land. Jour. Indus, and Engin. 
Chem., 2 (1910), No. 4, pp. 133-135. 
