70 ADDRESSES 



KIND OF UNDERLYING ROCK AN IMPORTANT CONSIDERATION. 



We must not fail, however, to consider the kind of rock from which the 

 soil has been formed, for this has an important influence in determining its 

 nature. In this state it is especially important to know whether the soil is 

 derived from limestone or whether it is derived from sandstone and shale. 

 This is due to the influence which the rock has in determining the 

 amount of lime which will be found in the soil. Other things being equal 

 a soil formed from a limestone will always have more lime than one derived 

 from sandstone and shale. A great many people, however, make the mistake 

 of assuming that a soil formed from limestone necessarily has a large amount 

 of lime in it, which is not always the case, especially in the surface soil. 

 This is due to the fact that lime is very soluble in carbonated rain water and 

 may be practically all leached out; in fact, so nearly all of it may be removed 

 through leaching that we may have an acid soil formed from a limestone. 



In our studies last summer in the western half of the state, where the glacial 

 drift is composed very largely of ground-up limestone, we found that the sub- 

 soil, within three feet of the surface, would often effervesce, when treated with 

 hydrochloric acid, showing the presence of a large amount of lime. Very seldom, 

 however, would such effervescence take place within 18 inches of the surface 

 while the surface soil usually gave an acid reaction. In the eastern half of the 

 State where the soils are derived very largely from sandstone and shale there 

 was very seldom any effervescence even in the subsoil, indicating a rather low 

 lime content. Some limestone layers, however, occur throughout the south- 

 eastern part of the State and it is necessary to be on the lookout for these as 

 their influence is shown by an increased productiveness in the soil. In fact, one 

 must know the character of the underlying rocks in order to understand the 

 various peculiarities of the soils. . In this part of our work the geological maps 

 will be of much assistance to us. 



How THE SOIL WAS MADE. 



It is also important to understand the processes of formation and the differ- 

 ences which may have resulted from a variation in these processes. Mention 

 has already been made of the formation of black soils under swampy conditions. 

 Those of you who are familiar with the conditions in Brown, Clermont, Hamil- 

 ton, southwestern Clinton, western Highland or southern Warren counties know 

 of the "white soils" which are found on the level areas there, as well as in some 

 other sections of the State. You have doubtless noted that these "white soils" 

 do not occur where the surface is rolling. Their formation is due to certain 

 process .which have gone on under intermittent wet and dry or stagnant water 

 conditions. If the surface is not sufficiently level for the water to stand several 

 days after a rain these processes are not brought about and the "white soil" 

 is not formed. 



THE SIZE OF THE SOIL PARTICLES. 



Another very important property of the soil, which must be considered in 

 making our classification, is that of texture. By this we mean the relative pro- 

 portion of the particles of various sizes which determine whether the soil shall 

 be called a sand, a loam, a clay or some intermediate class. The texture is the 

 most important physical property of the soil because of the important influence 

 which it has upon the water-holding capacity and cultural properties. Through 

 constant practice one may become very expert in judging of textural differences. 

 In order, however, to secure the greatest uniformity in this classification, samples 

 are collected and mechanical analyses made in the laboratory in order to furnish 



