48 
Absorption of Phosphate of Lime; and 
wash a g^ootl deal of this vahiable fertilising substance into the 
subsoil, and render it unavailable to the young turnip-plant, if 
the amount of soluble phosphate which is usually added to the 
soil were as large as in my experiments. 
But practically our dressings of superphosphate are applied in 
very different proportions. Supposing a heavy dose of 6 or 8 
cwts. of a concentrated superphosphate to have been added to 
only 2 or 3 inches of surface soil, we shall find on calculation 
that the proportion which the earth in the field bears to such 
dressings is many hundred times greater than that which the 
12 oz. of soil used in my experiments bears to the soluble phos- 
phate then supplied ; whilst in relation to 3 or 4 inches of 
surface soil, the quantity of soluble phosphate contained in G or 
8 cwts. of a rich superphosphate is so small that we cannot 
detect by analysis any difference in the amount of phosphoric 
acid present in the soil before and after it has received such a 
dressing of superphosphate. Although, therefore, a limited 
quantity of this loamy soil left a considerable proportion of 
A aluable phosphate in solution, I think we may rest assured that 
even in the most unfavourable circumstances the complete absorp- 
tion of this valuable fertilising constituent is secured in practice 
by the large amount of soil through which its solution has to 
pass. 
Absorption of Soluble Phosphate hij Calcareous Soil. 
Experiment B. — I next selected for experiment a calcareous 
soil, Avhich contained in 100 parts — 
Moisture 3"62 
Organic matters 4'23 
Carbonate of lime 67'5() 
Oxides of iron and alumina 7"54: 
Ma'^nesia '44 
Potash and soda 'TS) 
Insoluble siliceous matter (fine clay) 15'88 
100-00 
The preponderating constituent, the carbonate of lime, was 
h"re found in a finely divided state, as is frequently the case in 
chalky soils. 
■\^lh. (or 10,500 grains of this Calcareous Soil, 218-22 grains of Super- 
phosphate {<:ontaiiiing 81 '17 grains of Soluble Phosphate), and 3 pints (or 
26,250 grains) of Distilled Water mre mixed, as in Experiment A. 
After 24 hours, 7000 grains of the liquid being drawn ofT, were found to con- 
tain 2'23 grains of bone-earth ; so that the whole 3 pints held 
in solution 8-3(j grains of bone-earth. Hence, since the whole 
amount of bone-earth in the mixture was 81'17 grains, the 
IJ lb. of soil had absorbed 72*81 grains in 24 hours. (The 
