44 
Absorption of Phosphate of Lime , and 
3. The soil may contain already an abundance of phosphates 
in a sufficiently available condition to meet the requirements of 
the turnip-crop. In that case it is plain a mineral superphos- 
phate cannot produce anv effect. 
4. Tuough highly desirable for the growth of turnips, mineral 
superphosphate of lime does not provide organic matter, nor 
potash or carbonate of lime. Some soils, especially sandy soils, 
are greatlv deficient in all these elements of fertilitv ; and as 
superphosphate, unlike farmyard-manure, does not supply them 
all, the turnip-crop, not finding the proper description of food 
in the soil which it requires, becomes diseased or fails altogether, 
though superphosphate may have been used in large doses. 
There are thus at least four essentially different conditions to 
which root-crops may be exposed with respect to soil and purely 
phosphatic manure. 
The first being the most frequent, perhaps, may be called 
the normal condition in which we find turnips. On many farms, 
where a rational system of rotation is pursued, and no sign 
of disease in the root-crops has ever been noticed, superphos- 
phate is the onlv manure which is directlv applied to swedes or 
turnips. Notwithstanding the absence of organic matter and 
ammoniacal salts in the phosphatic manure, good root-crops are 
generally obtained when the land, more or less stiff in character, 
has been well cultivated in autumn and during the early part of 
spring, and a finely-pulverised surface-soil been obtained by 
■these means. Such land contains an amount of clay which in 
most cases provides root-crops with an abundance of all the 
necessary soil-constituents. But nevertheless an economical 
supply of superphosphate at the first period of growth seems to 
be most beneficial. 
The acknowledged power which purely phosphatic manures 
possess of pushing on the voung turnip-plant appears to indicate 
that but very few soils contain an amount of phosphoric acid 
which renders the direct application of superphosphate altogether 
superfluous. A great number of soil analyses made by many 
chemists of note have indeed proved this to be a fact. 
It is worth our while to notice also the care which is taken by 
Nature to provide plants at their earliest periods of existence 
with a constituent which possesses so remarkable an effect in 
pushing on the young plant, but is seldom present in soils 
in larger proportions than a mere fraction of a per cent. On 
examining the ashes of the seeds of all plants, it will be 
found that all contain much phosphoric acid, either in combi- 
nation with alkalies, or with lime or magnesia. During the 
germination of the seeds the phosphates contained in them 
appear to be rendered soluble. The most important mineral 
