18 AMERICAN AGRICULTURE. 



degree. Paring and burning, (by which, the surface con- 

 taining vegetable matter, is collected into heaps and fired, 

 reducing the mass to a charred heap, which is then spread 

 over and mixed with the soil,) produce the same result. 

 This is a practice which has been long in use in different 

 parts of Europe ; but although attended with immediate and 

 powerful results, it is too expensive for general introduction 

 into a country, where labor is high, and land and its products 

 comparatively cheap. 



Wherever frosts and snow abound, the plowing of clay 

 lands for spring crops, should be done in the autumn if prac- 

 ticable ; by which their adhesiveness is temporarily destroyed, 

 the earth is enriched by the snows, and finely pulverized 

 by the frost, and they are left in the finest condition for early 

 spring sowing, and without additional working. If plowed 

 in the spring, it should be done when they are neither too 

 wet nor dry ; if the former, the earth subsequently bakes, and 

 for a long time, it is almost impenetrable to the hoe or the 

 teeth of the harrow ; if too dry, they are so compact as to be 

 turned over only with great effort, and then in solid lumps. 

 The action of the atmosphere, will pulverize these masses 

 of baked earth after a time ; but not sufficiently early in most 

 of our northern states, for the convenience or advantage of 

 such crops as are immediately to follow the plowing. For 

 much of the South, plowing clay lands in the autumn is worse 

 than useless ; as the loose earth thus thrown up, is soon re- 

 duced by the heavy winter rains to a compact surface, ap- 

 parently as unfitted for cultivation, without subsequent plow- 

 ing, as the incrustations of lava from a volcano. 



No soils are so tenacious of the manures which may be 

 incorporated with them as the clays. They form an inti- 

 mate combination, both mechanical and chemical,* and hold 



* By mechanical, in the sense above used, is understood the external 

 relation of bodies, which is nearly equivalent in its meaning in this 

 connection, to artificial. Thus the clay envelopes the manure* and 

 from its impervious character shields it from escape either by drainage 

 or evaporation, and almost as effectually, as if it were enclosed in an 

 earthen vessel. 



By chemical is meant, its internal or constitutional character. Thus 

 clay not only absorbs the gases which are brought into contact with it 

 from manures, from moisture and from air, as a sponge absorbs water ; 

 but it also forms new combinations with them, which change the ori- 

 ginal nature of these elementary principles, and from light evanescent 

 gases, they become component parts of solid bodies, in which condi- 

 tion they are retained till exhausted by the growing vegetation. 



These terms are important, and should be fully understood. For 



