64 
Absorption of Phosphate of Lime ; and 
IG. Chalkv and marly soils possess this property in a higher 
degree than clay or sandy soils. 
17. The absorption of soluble phosphate by soils is never 
instantaneous, but requires some time. 
18. In practice the large extent of absorbing surface and heavy 
weight of the soil through which a solution of soluble phosphate 
has to pass before it can escape, secure its perfect absorption. 
19. Plants do not take up the acid biphosphate or soluble 
phosphate as such. 
20. Since the soluble phosphate in superphosphate of lime is 
rendei-ed insoluble in all soils, and the first as well as the after- 
growth of turnips is alike promoted by insoluble phosphates, it is 
erroneous to consider that soluble phosphate feeds the turnip-crop 
in its first stages of existence, and insoluble phosphate sustains 
its after-growth. 
21. The doctrine that, of the phosphates in a turnip-manure 
one-half should be soluble, and the other insoluble, is based on 
erroneous speculations. 
22. Of two turnip-manures containing an equal amount of 
phosphates, that which contains the largest amount of soluble 
phosphate is more valuable than the other containing the largest 
amount of insoluble phosphates, both manures being alike in 
other respects. 
23. In preparing superphosphate from mineral phosphates, 
the latter should be rendered soluble as completely as possible. 
24. Superjihosphate is not deteriorated by keeping for any 
lenofth of time. 
25. When incorporated with the soil the fertilising properties 
of superphosphate are retained for any reasonable length of time, 
and its effects frequently seen in the barley-crop on land on 
which turnips were grown in the preceding year with super- 
phosphate. 
26. The secret of the energetic action of superphosphate 
depends on the production of most minutely subdivided or pveci- 
pitated insoluble phosphates within the soil itself, and not on the 
supposed, but erroneous, direct assimilation of soluble phosphate 
by plants. 
27. Precipitated insoluble phosphate of lime is vastly more 
bulkv and more soluble in pure water than the finest powder 
obtained by mechanical means. 
28. The more rapidly and completely the soluble phosphate in 
commercial superphosphates and turnip-manures is precipitated, 
and rendered insoluble in the soil, the more energetic will be its 
elfcct upon the turnip-crop. This advantage is best secured by 
applying the manure with the liquid-drill. 
29. The application of superphosphate by the liquid manure 
