CLASSIFICATION. 227 



The preceding considerations are more than sufficient to give a 

 precise idea of what is to be understood in regard to the composition 

 of arable soils. Nevertheless, with a view to making the subject 

 more complete, I shall quote a few of the analyses of arable soils, 

 published by different chemists at a time when a certain importance 

 was attached to researches of this kind. I may remark generally, 

 that from the whole of the analyses of good wheat lands which have 

 hitherto been made, it appears that carbonate of lime enters in con- 

 siderable quantity into their composition ; and theory, in harmony 

 with practice, tends to show that it is advantageous to have this 

 earthy salt as a constituent in the manures which are put upon soils 

 that contain little or no lime. 



Analysis of a soil under the variety of rape called colza, by M. 

 Berthier : 



Silica 78.2 



Alumina 7.1 



Peroxide of iron 4.4 



Lime 1.9 



Magnesia 0.8 



Carbonic acid t 1.4 



Water 5.8 



This soil was dried in the air, after having been reduced to pov/- 

 der ; it lost 34 per cent, by drying. It is remarkable that it con- 

 tains no trace of organic matter, the rather as it was held favorable 

 for colewort. M. Berthier believes that this soil would gain in fer- 

 tility by the addition of a certain quantity of calcareous matter, and 

 M. Cordier* explains its inability to grow grain to advantage from 

 the deficiency in lime. The stalk of the grain gniwn in this soil is 

 weak, especially in wet seasons, and the seed is particularly apt to 

 shake out when it is ripe. 



If the presence of lime in a wheat soil is a guaranty against loss 

 by shaking in harvest, M. Berthier's analysis is still far from proving 

 that the presence of lime in a soil is indispensable, inasmuch as 

 beautiful wheat crops are grown in the neighborhood of Lisle without 

 lime. In proof of this fact, I shall here cite the analysis of one of 

 the most fertile soils in the world, the black soil of Tchornoizem, 

 which Mr. Murohison informs us constitutes the superficies of the 

 arable lands comprised betvt^een the 54th and 57th degrees of north 

 latitude, along the left bank of the Volga as far as Tcheboksar, from 

 Nijni to Kasan, and stretching over a still more extensive district 

 upon the Asiatic side of the Ural mountains. Mr. Murchison is of 

 opinion that this land is a submarine deposite formed by the accumu- 

 lation of sands rich in organic matters. The Tchornoizem is com- 

 posed of black particles mixed with grains of sand ; it is the best 

 soil in Russia for wheat and pasturage ; a year or two of fallow will 

 suffice to restore it to its former fertility after it has been exhausted 

 by cropping ; it is never manured. 



M. Payen found in this black and fertile soil : 



 On the Agriculture of French Flanders, p. SCKJ, <in French.) 



