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tain knowledge of the power with which the plant takes up its food 

 from the soil, unless, by microscopic examination, and by experiments 

 such as those of Hales, some estimate be formed of the combined 

 effects of capillary and osmotic action in drawing up liquids of various 

 composition. 



The special mineral food required by the cotton plant, and the 

 amount of this food, remain to be examined by analyses of the ash, 

 which will form another part of the investigation. Some statements 

 with regard to the nature of the mineral constituents have been made, 

 drawn from the results of Dr. Jackson's analyses, and all these sub- 

 stances needed by the plant have been seen to exist in the soil. As 

 to the extent to which they are withdrawn from the soil by cultiva- 

 tion, it may be remarked generally that cotton is by no means an 

 exhausting crop under proper management. 



The great mass of the plant root, stem, branches, leaves, and 

 emptied boles remains upon the field, and is ploughed into the soil, 

 which is enriched by the rapid decay of the organic matter. Nothing 

 is removed except the fibre and seed, and a large proportion, if not 

 the whole of the latter, is by judicious planters * returned to the 

 land ; cotton seed is in fact almost the only material used as manure 

 in the cotton region of America ; a large amount is added to the 

 soil by the ordinary mode of planting, the seed being thickly strewn 

 by handfulls in a continuous row, upon which, after thinning, but a 

 few plants are allowed to remain. The cotton fibre, which constitutes 

 the saleable product, and is absolutely carried off from the land, must 

 be looked upon as a very light crop ; a bale of 400 or 500 Ibs. to 

 the acre is sometimes obtained under favourable circumstances, but 

 this is much above the average for upland cotton. The fibre yields 

 1 or 1 per cent, of ash, so that at the most 7 Ibs. of mineral matter 

 per acre will be removed from the soil annually. 



According to Johnston (Lectures on Agricultural Chemistry, p . 2 1 6 ), 

 a crop of wheat of 25 bushels to the acre removes from the soil, 

 in the grain alone, about 1 7*65 Ibs. of mineral matter ; a crop of 

 barley of 38 bushels carries off, in the grain, 46*98 Ibs. ; a crop of 

 oats of 50 bushels, in the grain, 58 '05 Ibs. According to Liebig 



* The practice of selling cotton-seed from the plantation is one to be strongly 

 deprecated ; it is beginning to be common in some districts, owing to the increasing 

 manufacture of cotton-seed oil and exportation of the cotton seed-cake to Europe. 



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