Phospliatic Manures fyr Root- Crops. 
45 
food-constituent is thus provided bv the seed itself, and placed 
within easv reach of the infant plant just at a time when the 
amount of phosphoric acid in almost all soils would be inade- 
quate to induce a vigorous development of the whole vegetable 
organism. 
Direct experiments, extending- over a period of five years, 
have shown me that on the moderatelv tenacious calcareous clav 
soils on our farm, as large an increase in the produce of swedish- 
tumips may be obtained with bone-ash treated with sulphuric 
acid, as bv any other of the numerous fertilising mixtures which 
I have emploved in field-trials. My own experience receives a 
confirmation in the practice of many farmers who grow good root- 
crops on soils similar in composition to ours, with nothing else 
but 3 or 4 cwts. of superphosphate, the composition of which 
exhibits neither organic matter nor salts of ammonia. 
The soils on our farm, on which such a dressing was applied 
with most signal success, resembled much in composition and 
general character, the field selected for experimental trials in 
1860. The soil in this field contains hardly anv sand that can 
be separated by the mechanical processes of washing and decan- 
tation, and consists of a mechanical mixture of clav, calcareous 
gravel, and organic remains. An analysis of it furnished the 
following results : — 
Moisture (when analysed) 3-960 
Organic matter and water of coinbiuatiou .. .. 9-616 
Oxide of iron and alumina 19-660 
Carbonate of lime 3"805 
Sulphate of lime •345 
Phosphoric acid -075 
Ma<niesia -783 
Potash 1-239 
Soda -090 
Insoluble siliceous matter (chiefly cLiy) . . . . CO-525 
100 O'JS 
It will be seen that this soil contains a notable quantitv of avail- 
able potash as well as lime and organic remains, and, like most 
others, contains but little phosphoric acid. 
On clay soils of a similar chemical constitution, I believe the 
application of a sufficient quantitv of soluble phosphate will be 
iound to render the direct supply of other fertilising matters 
superfluous in growing turnips. At all events the result of 
numerous experiments has shown me that on such soils nitro- 
genised matters do not increase the efficacy of soluble phos- 
phates in a turnip-manure. 
It has been stated, in the second place, that the exclusive 
employment of mineral superphosphates for root-crops is pro- 
