va 
8 BULLETIN 149, U. S. DEPARTMENT OF AGRICULTURE. 
but not too great a concentration, is used stimulating effects are to be. 
expected in some cases at least. itr fact it is to be ane although | 
not yet clearly demonstrated, that in greenhouse practice and in 
botanical research, where the results obtained might justify the ex- 
pense involved, the radio-elements may prove of very great value, as 
they have done in other branches of science. When consideration, — 
however, is taken of the scarcity of these elements, it does not follow 
from any experiment so far described that such elements can have 
any practical application as a fertilizer in general farming. To 
increase the activity of the atmosphere above the soil with radium 
emanation would not be feasible in field practice, neither would it 
be practical to add such a quantity of radioactive material to the soil 
that the emanation in the under ground air would be increased te 
even the very low concentration used in Stoklasa’s experiments, and 
the same may be said with regard to making irrigating water radio- 
active. 
COMPOSITION OF RADIOACTIVE MANURE, 
The source of the so-called radioactive manures consists of the 
residual rock from which carnotite or other uranium ores have been 
extracted; or of uranium ores which contain too low a percentage 
of uranium to make it profitable to extract the radium. Since an ore 
containing as low as 2 per cent of uranium oxide can be profitably 
used in the manufacture of radium, it is not to be expected that this 
percentage of uranium, or its equivalent of radium, will be found in 
any radioactive manure. 
In the following table is given the composition of samples of radio- 
active materials hich have been apphed as a manure. 
Analyses of samples of radioactive manure. 
{ 
Constituent. A B Constituent. A B 
Silica(SiOp)essee see aos oee 80. 44 85. 90 | Ce anhydride (P20s).|........-- Trace. 
Oxide of iron and alumina “Soluble phosphoric acid’’. . Sis) eoseeoaeen 
(Fe20O2+AloO3).......------ 2. 20 8.65 || “ Water, volatile organic mat- 
Mime (CaO) ee sons ses ace ee silt see cose 91 Die ee apes WEN ee 10. 54 0. 93 
Maenesia: (MeO) ae soccer aie Seen -95 || “Soluble salts, soluble free 
SodaGNae) sas een weenie - 50 acids) ee N See See eas OE 32 eee mana 
Pate shih(Kas@)) esi ds ie as aa eee 104 | Uranium (U).............c...| ‘Trace 1/60 
Sulphide (S) SA Beto boocbosauollauancseas .16 SS 
“Sulphuric acid”’...........- BidOs|eo ce he Nctivity.6c ee ee 03 U . 037U 
A. Radioactive manure. Analysis according to Foulkes, Bul. Bureau Agricultural 
Intelligence and of Plant Diseases, 8, 1112. This apparently represents ore from which 
the uranium has been extracted. The acidity of the material was equivalent to 65 grams 
of sulphuric acid per kilogram. a 
B. Radioactive manure. Analysis by author. This material represented the originat 
ore and therefore did not contain any free acid. 
FIELD TESTS WITH RADIOACTIVE MANURE. 
Field tests with radioactive manure (A in table) have been made 
by Foulkes! in England. The material used contained only a trace 
of uranium, but had an activity equal to 0.03 times that of uranium. 
1 Bul. Bureau of Agricultural Intelligence and of Plant Diseases, 3, 1111 (1912). 
