REPORT OF THE CHEMIST. 171 



plants grown in the oriciual and in tLe diluted soil, we will find the roots iu the lat- 

 ter more lully diffused, larj^er, uud better developed, not couliued to the crevioos ol" a 

 hard clay, but permeating the entire luaes, and evidently haviuii fully a.s extensive a 

 surface coutaet with the fertile soil particles as was the case in the original soil. 

 Hiiw far this dilution may bo carried out without detriment would vary with different 

 plants and soils, and must largely be a matter of experiment. A plant capable of 

 devfiopiiig a very large root surface can obviously make up by greater spread ibr a 

 far greater dilution than one whose root surface is in any case but small. The former 

 tlourishes even on poor sandy soils, whilst the latter succeeds and is naturally found 

 on rich heavy ones only, although the absolute amount of plant food taken from the 

 soil may be the same in cither case. 



It is ob^ iouB that without a knowledge of the respective depths and penetrability 

 of two soils a comparison of their plant oonstituouta will be useless. The surface soil 

 with its processes of nitrification, oxidation, carbonic acid solution, &c., in full prog- 

 re.s.s must always be distinguished from the subsoil iu which these processes are but 

 feebly developed, and where the store of plant food, in which it is generally richer 

 tban a surface soil, is comparatively inert. Hence the obvious importance of samples 

 correctly taken and the necessity of intelligent and accurate observation on the snot. 



The concentration of the available portion of the plant foed of soils in their finer 

 portions has become a maxim. A strong soil is invariably one containing within 

 leach of a plant a large amount of impalpable matter, although the reverse is by no 

 means generally true. 



A comparisou of the composition of soils of known productiveness, and character- 

 ized iu their u.'itural state by certain invariable featiu'es of plant growth, soon reveals 

 the existence of definite relations, not only to the absolute amounts of certain in- 

 gredients present in the .soil, but also to their relative i)roportions. No ingredient 

 exerts in this respect a more decided inlluence than lime, its advent in relatively large 

 proportion, other things remaining equal, changing at once the whole character of 

 vegetation, so as to be a matter of popular remark everywhere. Only it is not popu- 

 larly known, nor has it been defirdtely recognized by agricultural chemists thus far, 

 that it is the lime that brings the change. 



Tbe amount of the dillerciit soil coustituentvS wliicli may be considered 

 the minimum consistent with fertility lias already been j;:iveu. 



OT<r THE GEOLOGICAL CHARACTER AND DISTRIBUTION OF SOILS IN 



THE UNITED STATES. 



Whilst there is a vast variety of detail iu the character of the soils 

 of this country in regard to both their physical properties and chemi- 

 cal composition, still they may be classified under the two head.'^ of 

 soils of transport and soils of disintegration, geologically speaking. 



Soils oftranfiport include, as has been previously stated, all drift and 

 alluvial materials which have beeu worn from other i-ocks by atmos- 

 pheric agencies and transported to their existing positions l)y ancient 

 glacial action, by winds, and by waters. These embrace the majoiity 

 of all soils occurring in the United States. 



Drift soils. — These occupy the principal portion of the States lying 

 north of the Ohio and east of the Missouri Rivers. According to Pro- 

 fessor Dana they occur "over all New England Jind Long Island. New 

 York, New Jersey, and part of Pennsylvania, and the States west to 

 the western limits of Iowa and Minnesota. Beyond the meridian of 

 08O W., in the United States, they are not known. They have their 

 soutbern limit near the parallel of 39° in Southern Pensylvania, Ohio, 

 1 ndiana, Illinois, and Iowa, whilst the northern is undetermined. South 

 of the Ohio Kiver they are hardly traceable." (Dana's Geology* j). 52,s.) 



Without going into the details of the theory of ancient glacial action, 

 which has given rise to a large amount of study and an extensive litera- 

 ture, the term drift, as it is commonly employed in geology, includes 

 the sands, gravels, clays of various composition and texture, and bowl- 

 ders, more or less water- worn, all mingled in various proportions and 

 of various degrees of fineness, which have been transported Irom places 

 in higher latitudes by glacial action and deposited on the country rock 

 in varying thickness. 



