244 
Journal of Agricultural Research 
Vol. V, No. 6 
Rape was also grown upon sand. The sand employed was obtained 
from the Wausau Quartz Co., Wausau, Wis. It was an angular product, 
designated as No. 2, which passed almost completely through a sieve of 
40 meshes to the inch, but was half retained by a 60-mesh sieve. It con¬ 
tained small amounts of impurities, but no sulphates. Fifteen kgm. (33 
pounds) of this sand were placed in the usual boxes with the following 
fertilizer treatments: 
Boxes Nos. Gm. 
’Tricalcium phosphate (Ca 3 (P 0 4 ) 2 ). 12. o 
Potassium chlorid (KC 1 ). 4. 5 
_ Magnesium nitrate (Mg(N 0 3 ) 2 ).. 2.5 
Sodium nitrate (NaN 0 3 ). 8. o 
Calcium carbonate (CaCO s ). 5. o 
Iron chlorid (FeCl 3 ). 1. o 
3-4. Like 1 and 2-{-calcium sulphate (CaS 0 4 ). 12. o 
5-6. Like 1 and 2-|-sodium sulphate (Na 2 S 0 4 ). 12. o 
7-8. Like 1 and 2-fsodium sulphate (Na 2 S 0 4 ). 6. o 
All of the salts, except sodium nitrate, were mixed with the sand 
before planting, but this was applied to the growing plants in portions 
from time to time. At 84 days of growth, when the plants gave the 
usual signs of maturity, the crop was harvested. The yields of the 
air-dried rape crops are given in Table VI. * 
Table VI .—Average weights {in grams) of air-dried rape crops 
Treatment. 
Tops. 
Roots. 
Relative yields 
when complete 
fertilizer= ioo. 
Tops. 
Roots. 
i. Complete fertilizer. 
39 -o 
43. 0 
26. < 
31. 0 
4-5 
10. 0 
3-2 
3*5 
IOO 
no 
68 
80 
IOO 
222 
71 
78 
2. Complete fertilizer-j-calcium sulphate. 
3. Complete fertilizer-{-sodium sulphate. 
4. Complete fertilizer-j-X sodium sulphate. 
In these cultures the calcium sulphate was beneficial, but the sodium 
sulphate depressed the yields as compared with the basal complete ferti¬ 
lization. The data show this effect of the sodium sulphate least where 
the smaller amount of salt was applied. This again seems to indicate 
that the depressed effect was due, in part at least, to an excessive con¬ 
centration of soluble salts. If such an effect were appreciable, one would 
expect it to be more pronounced in the case of the sand than with soil 
on account of the lower absorptive power of the former, and such was 
the case. The calcium sulphate exerted a remarkable effect on the 
development of the rape roots in these cultures. An objection might 
possibly be raised that the beneficial effects upon root growth apparent 
with the soil cultures may have been due to imperfect separation of the 
