CHAPTER THIRTY-FOUR 



RELATION OF PLANT INDUSTRIES TO CLIMATIC PLANT 

 FORMATIONS 



The climatic conditions that restrict each of the great plant 

 formations to a definite region of North America also determine 

 to a large extent the location of many industries dependent upon 

 plants or plant products. It is self-evident that most industries 

 that directly utilize wild plants are located near those plants. 

 And for the same reason industries directly dependent upon crop 

 plants are usually located in regions where the particular crop 

 plants grow best. 



Climate and the production of crops. Cultivated plants are 

 affected in their development by climatic factors in much the 

 same way as wild plants. Temperature, moisture, and Hght 

 conditions must be favorable ; and each of the important crop 

 plants has its own requirements in this matter. 



Crop plants must not only be able to grow in a particular cli- 

 mate, as wild plants do, but they must yield a profit to the grower. 

 Peanuts, for example, can be grown in the Northern states, but 

 the yield is so small that they are unprofitable ; they produce the 

 largest yields in the Southern states, where the temperature is 

 high. A crop grown in the region whose climate is most favor- 

 able to that crop will produce a better quality and a greater re- 

 turn to the grower than the same crop grown in a less favorable 

 locality. The distribution of crop plants is determined, then, by 

 the same factors that limit wild plants, and in addition, by cer- 

 tain economic factors. 



Soil factors and crop production. Within each climatic region 

 the various crops, like wild plants, are further limited by the 

 great variety of soil conditions. Some soils are poorly drained, 

 others are over-drained, and still others show every gradation 

 between. Soils may be lacking in some of the necessary min- 

 eral salts, or they may have some salts in excess. They may have 

 a high humus content, or be nearly lacking in humus. Some 



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