224 SOILS. 



Stiff or strong soils share in the advantages and disadvantages 

 peculiar to clay ; they absorb a great deal of moisture, and they do 

 not dry readily, retaining obstinately a considerable quantity of wa- 

 ter. The humus which they contain, and the manures which are 

 spread upon them in the course of cultivation, remain with thera for 

 a long time, preserved as it were from the too active agency of at- 

 mospheric influences ; the fertilizing power of these substances is 

 further rarely interfered with by too great a degret, ^f dryness in the 

 soil. Nevertheless, in very wet seasons, and in years of extraordi- 

 nary drought, the advantages which I have enumerated disappear. 

 In wet seasons clay lands become immoderately humid, sometimes 

 they approach the state of mere puddle ; and on the contrary, under 

 severe and long-continued drought, they become so hard that the 

 roots of vegetables can no longer penetrate them, and then they 

 crack in all directions, and the roots perish for want of being prop- 

 erly covered. I might add that severe frost is the cause of etfects 

 disadvantageous in the same degree ; so that very stitf c.ays are 

 liable to the same bad effects under the influence of two causes dia- 

 metrically opposed : the great heal of summer and the severe cold 

 of winter. 



In such soils all agricultural operations are often impracticable ; 

 changed into a liquid mud, neither horse nor plough can be put upon 

 them, or baked into a mass having the hardness of stone, the share 

 will not penetrate them. 



Light soils rarely accumulate an excess of moisture in their inter- 

 stices, so that they are liable to suffer under want of rain of even 

 short continuance. They are worked with infinitely greater ease, 

 and at much less expense ; vegetation upon them is quicker, and 

 harvests earlier ; but manure is less profitable than in clayey soils, 

 because the rains dissolve and carry it away. 



The defects of these two kinds of soils are precisely of a nature 

 to compensate one another, and it is in fact by a mixture, or that 

 which is equivalent to a mixture of these two extreme kinds of soil, 

 that those lands arc formed which are admitted to be the best adapted 

 to cultivation, and the most fertile of all. Messrs. Thaer and Einhoff, 

 in submitting to mechanical analysis an immense number of arable 

 soils, and in studying at the same time the system of culture best 

 adapted to these soils, and to their relative fertilities, have given us 

 results of great importance, and which may be made the basis of a 

 practical classification of arable soils.* 



An argillaceous or clayey soil properly so called, generally con- 

 tains about 40 per cent, of sand. If the quantity of sand be less 

 than this, the crop from sucii a soil will be more or less precarious, 

 and the tenacity will be s. ch, that considerable dilliculty will be ex- 

 perienced and necessary expense incurred in winking il ; such a 

 clayey soil, (liaving at least 40 per cent, of saiiil,) when it contains 

 a sufficient quantity of humus and is properly treated, may be regard- 

 ed as favorable for wheat. Barley succeeds better than wheat, whoa 



• Thaor's Rational Priixiplos of .Vsricnllurf, (in Krrnrli.; vol. ii. p. li^ 



