9 8 



SCIENCE AND SOIL 



4. The large tract of light, sandy lands in the north-central part 

 of the Lower Peninsula is called the " Jack Pine Plains." 



5. The peaty swamp soils, used especially for the growing of 

 celery, peppermint, etc., are so designated. 



In Table 20 is given the average composition of the soils from 

 each of these sections. The nitrogen reported is total, but the data 

 for phosphorus and potassium represent only the amount soluble 

 in acids, probably much stronger, however, than now commonly 

 used. The amount closely approaches the total in case of phos- 

 phorus, but probably represents less than one half of the total 

 potassium actually present in the soil. (A larger proportion of the 

 total potassium present in the newer, less- weathered soils is soluble 

 in acid than of the total potassium in the older leached soils found 

 in the states farther south.) 



TABLE 20. AVERAGE COMPOSITION OF SOME MICHIGAN SOILS 

 Pounds per Acre in 2 Million of Soil (about 6 Inches) 



1 The amounts given for deep peat represent the plant food in i million pounds 

 of the material, the specific gravity of which is about one half that of ordinary soils. 



These striking and valuable results obtained in a very prelimi- 

 nary general survey of Michigan soils clearly indicate the much 

 greater possible value of an extended and detailed investigation of 

 the soils of the state. The high phosphorus content of the Michigan 

 soils, especially of the great area of the wheat belt (3600 pounds), 

 is in marked contrast, not only with the extremely low phosphorus 

 content of the Jack Pine Plains (290 pounds, less than one 

 tenth as much), but also with the small supply of phosphorus in 

 the common upland soils of southern Illinois, central Missouri, 

 and the western parts of Kentucky, Tennessee, and other southern 

 states. 



