I860.] 



THE SOUTHERN PLANTER. 



649 



Chemical Composition of Soils— Applica- 

 tion of Manures, &c. 



Soils Lave been divided in the following 

 way, according to the proportion of clay, 

 sand, and lime, which they possess : 



1. Argillaceous soils, possessing little or 

 no calcareous matter, and above 50 per cent, 

 of clay. 



2. Loamy soils, containing from 20 to 

 50 per cent, of clay. 



3. Sandy soils, not more than 10 per cent, 

 of clay. 



4. Marly soils, 5 to 20 per cent of calca- 

 reous matter. 



5. Calcareous soils, more than 20 per cent, 

 of carbonate of lime. 



6. Humus soils, in which vegetable mould 

 abounds. Below the superficial soil there 

 exists what is called suhsoit, which varies in 

 its composition, and often differs much from 

 that on the surface. Into it the rain carries 

 down various soluble inorganic matters, 

 which, when brought to the surface by agri- 

 cultural operations, as trenching and subsoil 

 ploughing, may materially promote the 

 growth of crops. 



Humus, or decaying woody fibre, exists 

 in soils to a certain amount. This has been 

 called also, ulmine, or coal of humus. In a 

 soluble state it forms humic or ulmic acid. 

 Humus absorbs ammonia, and it is slowly 

 acted upon by the atmosphere, so as to form 

 carbonic acid by combination with oxygen. 

 Peaty soils contain much of this substance. 

 When peroxide of iron is present in such 

 soil, it loses part of its oxygen, and is con- 

 verted into the protoxide. 



Silica in greater or less quantity, is 

 found in all soils ; but it abounds in sand}?- 

 soils. In its ordinary state it is insoluble, 

 and it is only when acted upon by alkaline 

 matter in the soil that it forms compounds 

 which can be absorbed by plants. Silica, 

 in a, soluble state, exists in minute quanti- 

 ties in soils; the proportion, according to 

 Johnston, varying from 0.16 to 0.84 in 100 

 parts, while the insoluble siliceous matter 

 varies G0.47 to 83.31 in 100 parts. Wieg- 

 inan and Polstorf found that plants took 

 silica from a soil composed entirely of quartz 

 sand, from which everything organic and 

 soluble had been removed. The following 

 table shows the plants which germinated, 

 the height to which they grew previously to 

 being analysed, the quantity of silica they 

 contained when planted and the increase : 



' Silica in the Ash. 



f ,x « Silica bad 



Height. Seed. Plant. increased 



Barley.... 15 inches 0.034 0.355 10 times 



Oats. 18 " 0.0G4 0.354 5£ " 



Buckwheat 18 t; 0.004 0.075 18 " 



Vetch 10 " 0.013 0.135 10 " 



Clover... . 3£ " 0.009 0.091 10 " 



Tobacco.. 5 " 0.001 0.549 500 " 



Alumina exists abundantly in clayey 

 soils, but it does not enter largely into the 

 composition of plants. It has the power of 

 absorbing ammonia, and may prove benefi- 

 cial in this way. 



Lime is an essential ingredient in all fer- 

 tile soils. In 1000 lbs. of such soil, there 

 are, according to Johnston, 56 lbs. of lime; 

 while barren soil contains only 4 lbs. The 

 presence of phosphoric acid in soils, in the 

 form of phosphates of potass, soda, and 

 lime, is essential for the production of cer- 

 tain azotised compounds in plants; and sul- 

 phuric acid, similarly combined, is required 

 for the formation of others. 



A rough way of estimating the general 

 nature of a soil, is thus given by Prof. 

 Johnston : 



1. Weigh a given portion of soil, heat it 

 and dry it. The loss is water. 



2. Burn what remains. The loss is chief- 

 ly vegetable matter. 



3. Add muriatic acid to residue, and thus 

 the quantity of lime may be determined. 



4. Wash a fresh portion of soil to deter- 

 mine the quantity of insoluble siliceous 

 sand. 



Such an analysis, however, is by no 

 means sufficient for the purposes of the 

 farmer. 



The chemieal composition of a plant being- 

 known, conclusions can be drawn as to the 

 soil most suitable for its growth. This is a 

 matter of great importance both to the farmer 

 and to the planter. In order that the plant 

 may thrive, even in a suitable soil, exposure 

 and altitude must also be taken into account. 

 It is only by attention to these particulars 

 that agricultural and foresting operations 

 can be successful. As regards trees, the 

 following practical observations are given as 

 an illustration of what has been stated. 

 The .Scotch Fir thrives best in a healthy 

 soil, incumbent on a pervious subsoil, and at 

 a high altitude; Larch in loam, with a dry 

 subsoil, and a high situation; Spruce and 

 Silver Firs, will grow in a dry or peaty 

 soil; Oak in any soil and situation un- 

 der 800 feet above the level of the sea, but 



