SOILS AND FERTILIZERS 317 



differences in oxidation and hydration of the minerals which occasion 

 the color, but to some property in the soil which determines that 

 under similar climatic conditions the color of the one soil derived 

 from the same material of the Piedmont Plateau, laid down under 

 similar conditions, shall consistently be red, while the soil of an ad- 

 joining field may be yellow. The chemical properties exhibited in 

 the differences in color of these two soils, it is believed, have an effect 

 upon the chemical changes influential on the quality of the crop. 



That color is to a considerable degree indicative of productive- 

 ness is shown also by the change which takes place in the subsoil be- 

 tween the time when it is freshly turned up and when brought into a 

 condition favorable for crops. In the Atlantic Coast States, particu- 

 larly, it is not uncommon to find subsoils deleterious to crops if too 

 much of the material is turned up at any one time by the plow, and 

 it is interesting to watch a skillful gardener improve a piece of raw 

 land of such character. He adds a little manure and spades it in 

 lightly, and still the soil is not in first-class condition for a crop. 

 He lets this lie four or five weeks and respades and finds the color 

 gradually and slowly changing. It may take three or four years to 

 produce a fertile soil out of the raw piece of land or out of a subsoil 

 in this way, and his experienced eye can tell from the color changes 

 the rate of progress with which the change is taking place. The gar- 

 dener knows that by his methods of soil fermentation and by the 

 increased oxidation brought about by intelligent methods of han- 

 dling certain changes have taken place in what was formerly the raw 

 subsoil to fit the material for crop production. In this case it is not 

 the lack of organic matter, for this can be supplied at once, but it is 

 the form or the condition of the organic matter in the subsoil which 

 indicates to him unfavorable conditions for plant growth, and these 

 conditions he ameliorates or changes both by the addition of organic 

 manures and by judicious cultivation. 



The soil expert knows what can be accomplished by these arti- 

 ficial means, but he knows that no means are available to produce the 

 Cuban tobacco of high aroma on the yellow soils of the Norfolk series 

 or the Sumatra type of wrapper leaf of equally high quality on the 

 red soils of the Orangeburg series. He also knows from experience 

 that with the highest art of cultivation the black soils of the Ports- 

 mouth series will produce different crops or the same crops of dif- 

 ferent quality than will the black soils of the Houston series. 



In the glacial regions the black soils of the Marshall series and 

 the yellow soils of the Miami series are another striking example of 

 differences in crop adaptation indicated by color differences. The 

 greater productiveness of the darker soils is not dependent upon the 

 amount of organic matter, because two soils may have the same 

 amount of organic matter and yet have entirely different crop values, 

 but it is due to differences in the condition of the organic matter. 



The red soils of the Orangeburg series of the Coastal Plains 

 are stronger and more lasting under hard usage than the adjacent 

 yellow soils of the Norfolk series. The former will produce more 

 cotton and will stand more continuous culture with me same good 



