178 THE YEAR-BOOK OF AGRICULTURE. 



In Germany, Schleiden is attracting much attention by his masterly views on the phe 

 nomena of vegetation ; and it will surprise many to hear that he admits of no relation between 

 the fertility of a soil and the quantity of fertilizing matters expended upon it. "The good- 

 ness of the soil," he says, "depends upon its inorganic constituents, so far, at least, as they 

 are soluble in water, or through continued action of carbonic acid; and the more abundant 

 and various these solutions, the more fruitful is the ground." Arguing from this view, it 

 is not richness of soil or humus that produces the multiplied varieties of Alpine- plants in Ger- 

 many, or the absence of it that produces but few. " Soluble mineral constituents" are shown 

 to be the characteristic of our cultivated field; and "an agricultural plant" is defined as one 

 "distinguished from wild individuals of the same species by peculiar qualities which consti- 

 tute its fitness for culture, and which depend upon a modification of chemical action." The 

 amazing yield of Indian corn in Mexico from two hundred to six hundred-fold is something 

 which, with all our skill, we cannot accomplish, and is a fact in favor of the argument "that 

 in no case do the organic substances contained in the ground perform any direct part of the 

 nutrition of lants." The annual destruction of organic matter all over the earth is estimated 

 at one hundred and forty-five billions of pounds, equal to two and one-fourth billions of cubic 

 feet ; and if all vegetation depends on organic matter for nutrition, to satisfy this consump- 

 tion "there must have been, five thousand years back, ten feet deep of pure organic substance 

 on its surface." Another illustration is furnished by taking the number of cattle and other 

 animals in France in a given year, (1844,) and observing the amount of food they consume. 

 The process of nutrition would require 76,789,000,000 pounds of organic matter; six times 

 more than the whole number contribute of organic matter towards reproduction, and in one 

 hundred years "the whole organic material of the country would be consumed." 



Again: look at a farm. How much more is carried off from it than is given back again! 

 Generally the amount of its yield is three times greater than that of the organic matter it 

 receives; while of the manure applied, the greater part is not taken up, but imperceptibly 

 decomposed. Carbon is the most important of the constituents of plants: an acre of sugar 

 plantation produces 7500 pounds of canes, of which 1200 pounds are carbon, and yet sugar 

 plantations are rarely manured, and then only with the ashes of the burnt canes. With 

 bananas the result is still more striking: the yield is 98,000 pounds of fruit in a year from a 

 single acre, and of this 17,000 pounds more than a fifth is carbon; and the same acre will 

 give the same return year after year for twenty or thirty years; and the ground at the end 

 of that time will be richer than at the commencement, from nothing more than the decay of 

 the large leaves of the plant. Here in Europe, too, the difference in weight and in carbon 

 between the seed and the produce has often been noted: in wheat, 89 per cent; in red clover, 

 158 per cent. ; and in peas, 361 per cent. These facts afford evidence of a supply of carbon 

 derived from other sources than those commonly supposed to exist; and while we know that 

 seeds will germinate and become vigorous plants in pure quartzose sand, or in cotton-wool, 

 or on a board, we seem to have proof that the chief source of supply is the atmosphere. This 

 is an interesting point, which further research will verify : Schleiden shows the process to be 

 eminently simple. He says, in his work, of which a translation has been published by the 

 Horticultural Society "According to Link, Schwartz, and others, an acre of water-meadow 

 contains 4400 pounds of hay, which, when dry, contains 45-8 per cent, of carbon. The hay 

 then yields 2000 pounds of carbon, to which 1000 pounds may be added for the portion of 

 the year in which the grass is not cut, and the roots. To produce these 3000 pounds of car- 

 bon, 10,980 pounds of carbonic acid is requisite, which may be raised to 12,000 pounds, to 

 compensate for the nightly expiration. Now, Schubler has shown that an acre of so wretched 

 a grass as Poa annua exhales in 120 days (too low a computation) of active vegetation, 

 6,000,000 pounds of water. To supply the exigencies of the plants, therefore, it is only 

 necessary for the meadow to imbibe 3 grains of carbonic acid with every pound of water. 



Mr. Lawes has found, also, that in a plant of any one of our ordinary crops, more than 

 200 grains of water must pass through it for a single grain of solid substance to accumulate 

 within it. He states the evaporation from an acre of wheat during the period of its growth 

 to be 114,860 gallons, or 73,510,000 gallons per square mile. With clover, it is rather more: 

 with peas and barley, less. When we apply these calculations to a county or a kingdom, we 



