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8 > Page 8 of Chemical report of the soils, marls, clays, ores, coals, iron furnace products, mineral waters, &c, &c. of Kentucky / by Robert Peter, assisted by John H. Talbutt.

CHEMICAL REPORT. Because of the very small proportion of the essential ingre- dients of the soil, which are carried off in crops, as compared with the whole amount of the earth, taken to the depth through which the roots of plants absorb nourishment, it has been denied that it is possible by chemical analysis to show their diminution in the old field soil, as compared with the virgin soil. Indeed it has been logically demonstrated to be impos- sible. But, it should be recollected that when, by the acid digestion, we separate these essential soluble ingredients from the greater mass of the soil, left as sand and insoluble silicates, which amount to from about seventy-five to ninety-two per cent. of the whole, the probabilities of error in the determination of these minuter ingredients must not be calculated into the whole weight of the soil, but into that smaller part which we have thus extracted from it. Logic apart, the fact still remains, that in one hundred and forty-nine duplicate analyses, made by the writer for the Ken- tucky, Arkansas, and Indiana Surveys, in which the chemical composition of the virgin soil was compared, under similar conditions of treatment, with soil of a neighboring old field in the same locality, one hundred and twenty-two out of the one hundred and forty-nine showed a marked diminution of most of the essential ingredients of the soil in that of the old field as compared with the virgin soil. This certainly is not an accidental result. In the soil analyses at present reported the results are not so striking in this relation. Partly because the samples had not, in several cases, been collected with special reference to this investigation, and partly because of greater local variations of the soil in the regions in which they were obtained. In calculating the probable amount of exhaustion of the essential soil ingredients, it should be recollected that as much, and sometimes more, may be alienated from the soil by the solvent action of the atmospheric agents, while the surface is much exposed in the cultivation of hoed crops, than is absorbed and removed by the products. Hence the exhaustion of the soil is much more rapid under these cir- 144 8