LETTER OF TRANSMITTAL. 
Honolulu, Hawaii, July 1, 1916. 
Sir: I have the honor to submit herewith, and recommend for pub- 
lication as Bulletin No. 41 of the Hawaii Agricultural Experiment 
Station, a paper entitled " Phosphate Fertilizers for Hawaiian Soils, 
and Their Availability," by Wm. T. McGeorge, former chemist of the 
station. The use of phosphate fertilizer on Hawaiian soils is of ex- 
treme economic importance, owing to the unavailability of the large 
quantities naturally occurring in these soils. In the present paper 
several points of scientific and practical importance are brought out 
regarding (1) the influence of phosphate fertilizers on plant growth, 
(2) the availability of the naturally occurring phosphates, (3) the 
solubility of those phosphates as measured by various solvents, and 
(4) the chemical combinations in which phosphoric acid exists in 
Hawaiian soils. It appears that the primary factor in the nonavail- 
ability of phosphoric acid in Hawaiian soils is the peculiar physical 
condition of the soil and that phosphate fertilizers should be applied 
in a soluble form to produce the best results. 
Respectfully, 
J. M. Westgate, 
Agronomist in Charge. 
Dr. A. C. True, 
Director States Relations Service, 
U. S. Department of Agriculture, Washington, D. O. 
Recommended for publication. 
A. C. True, Director. 
Publication authorized. 
D. F. Houston, 
Secretary of Agriculture. 
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