EXACT CONST -JtOENTS OF SOME UNFRUITFUL SOtLS. 287 



II. — BARREN OR UNFRUITFUL SOILS. 



Soils are unfruiiful or altogether barren, either when they contain too 

 little of one or more of the inorganic constituents of plants, or when some 

 substance is present in them in such quantity as to become hurtful or 

 poisonous to vegetation. The presence of sulphate of iron in the subsoil 

 just described is an illustration of the latter fact. In what way the defi- 

 ciency o^ ceriaim substances really does allect the agricuhural capabilities 

 of the soil will appear from the tbllowing analyses : — 



1. 2. 3. 4. 



Moor land soil, Another Sandy Soil on the 



near Aurich, soil from soil from Muschel- 



East Friesland. the same Wettingen kalk, 



neighbour- in Liine- near Mlihl- 

 Soil. Subsoil. hood. burg- hausen. 



Silica and auartz Sand . . 70-576— 95190 61576 96000 77780 



Alumina 1050— 2520 0450 0500 9 490 



Oxides of Iron 0-252— 1-460 0-524 2000 5 800 



Oxide of Manganese . . . trace — 0048 trace trace 01 05 



Lime do.— 0-336 0320 0001 0866 



Magnesia 0012— 0125 0130 trace 0728 



Potash trace — 0072 trace do. trace 



Soda do. — 0-180 do. do. do. 



Phosphoric Acid .... do. 0034 do. do. 0003 



Sulphuric Acid do. 0020 do. do. trace 



Carbonic Acid — — — — 0200 



Chlorine trace — 0015 trace trace trace 



HumicAcid 11-910- — 11-470 0200 0732 



Insoluble Humus .... 16-200— — 26530 1-299 0-200 



Water _ _ _ _ 4096 



100 100 100 100 100 



Each of these analyses is deserving of attention. 



1°. That the barrenness of the moor-land soils (1 and 2) is to be at- 

 tributed to their deficiency in the numerous substances of which they 

 contain only traces, may almost be said to be proved by the fact — one 

 long recognised and acknowledged on many of our own moor-lands and 

 peaty soils — that when dressed with a covering of the subsoil they be- 

 come capable of successful cultivation. The analysis of the sub.soil in 

 the second column shows that it contains all those mineral constituents in 

 which the soil itself is deficient — and to the eflect of these, therefore, the 

 improvement produced upon the soil by bringing it to the surface is alto- 

 gether to be attributed. 



2°. The sandy soil, No. 3, is evidently barren for the same reason as 

 the moorland soils, 1 and 2. The soil No. 4 rests on lime-stone, and 

 was mixed with 7 percent, of lime-stone gravel, and contains a great 

 number of the substances which plants require — but its unfruitfulness is 

 to be ascribed to the want of potash and soda, of sulphuric acid and of 

 chlorine. Wood ashes and a mixture of common salt with gj'^psum or 

 sulphate of soda, would probably have remedied these defects. 



3°. Among the fertile soils to which I recently directed your attention 

 (p.^284) was one frpm Belgium, in which the proportion of organic 

 matter was less than half a per cent, of its whole weight. In the above 

 table, on the other band, we have two nearly barren soils, containing 



