s 
EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 111 
TaBLE LXVI.—Yields of oats obtained in four pot experiments with various 
types of soil. 
Yields of oats, average of four pots. 
a8 Application 
Fertilizer. per acre. | Copctal Jeeta Hiedmont, Piedmont 
: F ed Lan choco nt, 
Plain soil. esi = ee gray soil. 
Pounds. Grams. Grams. Grams. Grams 
IACIGEPHOSPHALCH Ac acscssisicig-sicsoaaccsoenc 2 37.9 42. 37.5 38. 1 
OS TSR Tm geek es Ba ENA Be aS £8 120 30.9 43.2 28.6 35.7 
INOMERUHIZETB Ee a ws ccece cscs vac sceckmesncleseeses=ccins 33. 9 46.5 32. 8 34. 4 
Nitrate ofsoday. ts eeac shee seas en ene 100 34.1 54. 6 45.2 39.1 
Polassiun Sulphaterecetcts tucweesmissetionciee 100 32.3 44.0] 45.5 37.8 
itrateonsoday . 208 s.--ceese eens aeleee <5 100 
Potassium Sulphate sarees ec cecouenceocs 100 \ vali gone 47-4 51-9 
NLTRACC OL SOU Beye asic cieis Siclepn ie cieelcioieie 100 
ACIGIDNOSDNAteia: a acca me scinccn sae sisi ainie 200 \ 45.5 60. 1 57.0 51.5 
Nitrate OfSodaes ss soe seein oe esse eee 100 
otassiumisulphateress ese aesceeeeee ne 100 46.8 65. 0 51.0 53. 0 
es phosphaterexaccece chee «css cssecetese 200 
HIT CE Meslclstalaicielacieleleisinisielsjetaia ecco see ccceces 25. 8 | 
With the exception of the Coastal Plain soil, the various types 
seemed to respond more readily to nitrogen than to phosphoric acid 
applications. On the basis of equal applications of phosphoric acid, 
however, the acid phosphate pots gave considerably better yields 
than those treated with raw rock phosphate, the latter material ap- 
parently producing no effect whatever. The rate of application, 
however, was so low,’ and the duration of the experiments so brief, 
that appreciable increases in yield could hardly be expected. 
In 1913 Johnson,? of the Virginia Truck Station, published the 
results of a fertilizer experiment in the growing of kale. This ex- 
periment was the outgrowth of one begun in 1908, the object of which 
was to determine the relative value of various fertilizer materials 
and the best quantities to apply, and also to determine the relative 
value of stable manure and clover as sources of humus both with 
and without lime. 
The fertilizer treatment was continued over a period of five years, 
but the results of only one year (1913) are recorded. The ground 
raw rock phosphate plots compared very favorably with the acid 
phosphate plots, but the best yields were obtained from the use 
of bone products, owing probably to the nitrogen contained in the 
latter. However, the limited data recorded render the results of this 
experiment inconclusive. 
The work of the Virginia station has not as yet been extensive 
enough to justify a comparison of acid phosphate with ground raw 
rock phosphate, particularly as in every experiment the applications 
of the latter material have been too light to get the full benefit from 
such an insoluble substance. 
1The amount of phosphoric acid applied was sufficient to add about 0.0014 per cent of 
P.O; to the first 9 inches of a soil of medium texture, 
2Va. Truck Expt. Sta., Bul. No. 9 (1913). 
