SPECIAL CROP SOILS 79 



yellowish or grayish in color. The surface soil varies from eight 

 to twelve inches in depth. The area is adapted to general farm 

 crops, with hay taking the lead. Permanent pastures are very 

 successful and the associated industries of dairying and stock 

 raising are extensively carried on. The chief grains grown are 

 winter wheat, corn and oats. 



Special Crop Soils. A number of soils occupying much smaller 

 areas than the four just described have been studied with refer- 

 ence to crop adaptation. Some of these are well suited to special 

 crops. The soils of the Portsmouth series are adapted to small 

 fruits and somewhat used for late truck. The soils of the Porter 

 series in the Blue Ridge section are used for apple growing. The 

 Norfolk fine sand, of the Atlantic coastal plain, is best suited to 

 the production of early truck crops. The Wabash clay loam of 

 the Mississippi delta is specially suited to the growing of sugar 

 cane. Crowley loams of Louisiana and Arkansas are well adapted 

 to rice-growing. The Clyde soils, of southern Michigan, are used 

 for such special crops as celery, onions, and sugar beets. The 

 Dunkirk series of soils of the lower Great Lakes are used for 

 orchards, vineyards, and general farm crops. 



FIELD AND LABORATORY EXERCISES 



1. Field and Weed Seeds in Soil. Try to prove that there are live seeds 

 in chance samples of garden soil. Put the soil in favorable condition for ger- 

 mination, keeping the moisture and temperature favorable, and see if any 

 seeds germinate. 



2. Germs in Soils. Examine a sample of garden soil for organic life by 

 testing the presence of mold germs. This may be done by taking two samples 

 of the same soil in two cans. Place one of these samples in an oven for half 

 an hour to kill all spores or other life present. Then in each can place a piece 

 of freshly toasted bread or freshly baked biscuit. Moisten these with water 

 that has been boiled and cooled. Cover both cans alike to exclude mold from 

 the air. Set them on a shelf and await developments. In which one does 

 mold develop first? The bread in this case serves as food on which the mold 

 can grow. 



3. Bacteria and Growth. Sterilize two samples of soil as in the above 

 exercise. In each plant wheat and moisten both with water which has been 

 boiled and cooled and is free from bacteria. Compare the growth in the two 

 lots of soil. 



4. Bacteria Cultures. If conditions are favorable for making bacteria 

 cultures, test samples of garden soil by making cultures from them. 



5. Soil inoculation may be illustrated by taking two flower pots which are 

 filled with the same kind of soil. Sterilize both of these in the oven. Into one 

 of them introduce a culture of clover bacteria by taking a few ounces of soil 

 where clover is growing thriftily. Stir it into a pot. Then plant clover, using 

 the same number of seeds for each pot. Compare the clover for the next six 

 or eight weeks, taking care to keep the moisture conditions and temperature 

 favorable for clover. 



6. The above exercise may be varied byusing an artificial culture for clover 

 obtained from the United States Department of Agriculture. 



