LIMING OF SOILS FROM A PHYSIOLOGICAL STANDPOINT. 13 
but this is certainly only a subordinate cause. The evil effects are 
mainly due to their high magnesia content, which will do little harm 
on soils rich in lime and poor in magnesia, but produces much injury 
on soils poor in lime rather than in magnesia. The more magnesia in 
relation to lime present in a soil the more injurious a certain additional 
quantity of magnesium compounds will prove. With the Stassfurt 
salts containing magnesium sulphate and chlorid this must be much 
more evident when they are applied in spring than when applied in 
autumn, since during the winter a part of the magnesium salts can be 
washed out as already stated or else turned into the less noxious car- 
bonate. To foretell whether magnesium limestone or the crude salts 
of Stassfurt would prove to be injurious manures the analysis of the 
soil would give the proper answer. 
The total amount of lime contained in the earth’s crust is larger than 
that of magnesia. The calculation of F. W. Clarke gives as approxi- 
mate numbers: Lime, 5.29 per cent; magnesia, +.49 per cent: or, 
calcium, 3.77 per cent; magnesium, 2.68 percent. But since the com- 
pounds of these elements are not uniformly distributed through the 
earth’s crust, regions exist in which magnesia predominates over lime 
and others in which lime predominates over magnesia. Manifold 
variations have indeed been observed. Frequent manuring: has, of 
course, changed these proportions from olden times in the uppermost 
‘stratum of the cultivated parts. The dung of animals fed with seeds, 
such as, for example, maize, oats, and barley. will of course be rela- 
tively richer in magnesia than that of animals fed mainly on grass, 
straw, and various other foliage. The latter manure will contain rela- 
tively more lime than the former. Thus, even without having recourse 
to direct liming, the lime content of cultivated land is often uninten- 
tionally increased. In the average fresh barnyard manure there is 
contained, according to Ville, 80 per cent of water, and among the 
mineral constituents 0.56 per cent lime and 0.24 per cent magnesia, 
forming a ratio of 1: 0.43. 
But while in the crust of the earth as a whole, as well as in most of 
the spring waters, lime predominates over magnesia, the reverse is 
observed in the oceans. Sea water contains about 33 per’ cent of 
soluble salts in the following proportions: Sodium chlorid, 78: mag- 
nesium chlorid, 11; magnesium sulphate, 5: calcium sulphate, 4: 
potassium sulphate, 2: traces of iodides, bromides, phosphates, ete.' 
' Marret calculates the following amounts for 1,000 parts of sea water (quoted by 
Liebig, Agriculturchemie. ) 
ERIM Ne eS ie 5 eS Rehan. Be OD 
ee a Be Da a eg a 4. 660 
ERNE SA Oe oS 6 i ee ee 1. 232 
Ee ee: a Se ee eo es 5. 152 
ee ee SE | ee ne en ee 1. 500 
