EFFICIENCIES OF PHOSPHATIC FERTILIZERS AS 
AFFECTED BY LIMING AND BY THE LENGTH OF 
TIME THE PHOSPHATES REMAINED IN PORTO 
RICAN SOILS 1 
By P. L. GilE, formerly Chemist , and J. O. CarrERO, Assistant Chemist, Porto Rico 
Agricultural Experiment Station 
INTRODUCTION 
Notwithstanding the fact that hundreds of field experiments have been 
conducted to determine the relative values of the different phosphatic 
fertilizers, only very few accurate quantitative data on this subject have 
been obtained. Failure to obtain data has, in most instances, been due 
to the usual difficulties attending tests of this kind, but in a number of 
cases it has been due to failure to ascertain whether any of the phosphates 
were applied in excess of the crop's requirements. Experiments con¬ 
ducted during the last 15 years with the different phosphates in pot cul¬ 
tures have been more fruitful of results in that they have demonstrated 
quite clearly several general factors influencing the efficiencies of the 
various phosphates. 
The experiments of Prianischnikov (21) , 2 Kossowitsch (i3), Jordan (9), 
Chirikov (2, 3), Truog (31), Wrangell (32), and Bauer (i) show that 
different crops vary greatly in their abilities to utilize the rock phosphates. 
The last four investigators named suggest that these differences in “feed¬ 
ing power" are correlated with the quantities of lime that are assimilated 
by the crop, or with the relative quantities of lime and phosphoric acid 
that are absorbed. 
That the character of the soil affects the efficiences of the phosphates is 
evident from many field trials and from the work of Kossowitsch (13) and 
Gedroiz (4). 
Carbonate of lime markedly decreases the efficiencies of bone meal and 
rock phosphate, but, according to the results of Kellner and Bottcher 
(jo, jj), Soderbaum (27, 28 , 2p), Nagaoka (19), Prianischnikov 
(21, 22 , 23 , 24), Kossowitsch (12), Liechti (14), and Mitscherlich (id, 17), 
it does not affect the efficiencies of basic slag, dicalcium phosphate, or the 
water-soluble phosphates. 
Investigations by Prianischnikov ( 21 , 24 ), Kossowitsch ( 12 ), Soder¬ 
baum (29, 30), and Mitscherlich and Simmermacher (18) show that the 
insoluble phosphates are appreciably more efficient when ammonium 
sulphate is applied with the phosphate than when sodium nitrate is used 
as the source of nitrogen. 
The effect which carbonate of lime exerts on the efficiencies of the phos¬ 
phates has become a matter of much practical importance since liming has 
become a general practice. It is especially important to know the effect 
of applications of lime such as would be required to satisfy the lime 
requirement of different soils. The work cited above, however, does not 
. 1 Accepted for publication May 2,1923. 
* Reference is made by number (italics) to “Literature cited,” p. 193-194. 
(171) 
Journal of Agricultural Research, 
Washington, D. C. 
aft 
Vol. XXV, No. 4 
July 28,1923 
Key No. B-19 
