EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE, 109 
VIRGINIA, 
In an article entitled “A Study of the Effect of Fertilizers on the 
Soluble Plant Food in the Soil, and on the Crop Yield,” Ellett and 
Hill, showed the impracticability of accurately correlating the solu- 
@uity of phosphates in a certain conventional solvent with their avail- 
ability to crops under soil conditions. The analytical work connected 
with the problem was checked against field results with corn ex- 
tending over a period of five years. 
The soil of the field used in this experiment was derived from the 
Shenandoah limestone, and consisted of a light gray (Hagerstown) 
loam, ranging from 6 to 10 inches in depth and underlain by a red- 
dish yellow clay subsoil. “The cropping history of this particular 
soil is not definitely known, but it has probably been under cultiva- 
tion for not less than 75 years.” The total phosphoric acid content 
(0.118 per cent) was ample, though only 0.07 per cent was shown by 
the ordinary hydrochloric acid digestion method of analysis. 
_ The annual application per acre of the various fertilizers and the 
yields of corn (grain) obtained are shown in Table LXV. Since 
none of the other phosphates was used in connection with carriers of 
nitrogen and potash, a comparison between them and acid phosphate 
is only possible where the latter was used alone. The results obtained 
on plots treated with mixtures of acid phosphate, nitrogen, and pot- 
ash are, therefore, omitted in the table. 
TaBLE LXV.—Yields per acre of corn obtained on plots receiving various forms 
of phosphoric acid (1907-1911). 
Plot Applica pete 
num- Fertilizer tion per| 1907 1908 1909 1910 1911 y 
ber acre for five 
: ; years. 
Pownds.| Bushels.| Bushels.| Bushels.| Bushels.| Bushels.| Bushels. 
1 | Acid phosphate. ............... 600. 0 46.61 | 45.00 42.95 37. 50 30. 53 40. 51 
DAs, Baar COH5. ns ss eae asek 200. 0 41.79 48. 21 41.79 30. 53 34. 82 39. 43 
Ree SEClODUSt et as ic oe eon ele . 99.6 46. 61 46.61 39. 64 25.01 36. 43 39. 00 
7 sd eas Tew GOS tS Ee See ee ee eee 99.6 43.93 Sppswell 2 eeyIul 27.32 34. 28 39. 59 
hel PHOMIAS SIA S225 22 osn = Ss. so 5 192.0 41.79 44. 46 39. 11 19. 28 31. 60 35. 24 
ty | eae OR eee 192.0 37.5 41.7 30. 00 21. 42 31. 07 32.35 
@|\-Acid=phosphate = 522222. 222. - 400. 0 39.11 38. 57 32. 68 14, 82 21. 43 29.32 
THELT) COM OV SV 1 Fe ae 2 a es (ee 43. 93 40. 18 36. 96 24. 64 19. 29 33. 00 
3 OAS eee CORE SOS See SR pee Al Dee ore 40. 71 51. 43 39. 64 24.10 24.10 35. 99 
1S ile 0 ES ee eee 42. 86 45. 00 36. 43 24. 10 30. 00 35. 67 
lis See ae COA as ee se sccwcees 42. 86 46. 61 43. 39 28. 92 37. 50 39. 85 
TESTE DEI YS ics cS oe a Se ieee er ae 1, 200. 0 43. 93 53. 57 52. 50 39. 65 47. 68 47. 46 
HOM SO Me eG Kets a epee ee eee ce cess 44. 46 47.14 39. 64 30. 00 34. 82 39. 21 
0. Vol aa CLO pfs ina | a Sk biciee 42. 86 53. 57 46. 08 30. 00 35. 36 41.57 
Doalaecse CLO ray ten. Sas coool cwoeeee 40. 71 62. 14 38. 03 15. 00 37. 50 44,59 
>), a ea die pe en | ere ea 40. 18 31. 07 36.96 | 17.85] 33.21 35. 35 
1Not included in average. 
The results obtained in this experiment are very confusing. If the 
difference in the yields of the check plots be considered for any 
ee 
iVa. Agr. Expt. Sta. (Blacksburg). Ann. Rept. for 1911-12, pp. 116-132 (1913). 
