108 ALFALFA FARMING IN AMERICA. 



tial things. All the rest that can be added will help ; 

 these two are indispensable. 



Other Functions of Lime. — What other func- 

 tions besides making the soil habitable for good and 

 useful bacteria does the carbonate of lime have in 

 the soil? 



It seems the very foundation of fertility itself. 

 The presence of much carbonate of lime in the soil 

 seems necessary to the formation of black humus. 

 In nature soils rich in lime become black loams. 

 Some good illustrations of this truth are seen in two 

 instances. In Mississippi and Alabama are soils 

 based on decaying limestone, the so-called "black- 

 prairie" soils. They are exceedingly rich, strong, 

 productive soils, among the best in the South. They 

 grow any sort of crops well, and especially do they 

 grow alfalfa luxuriantly. Most soils in the south are 

 very deficient in humus and without the dark brown 

 color. That is because most southern soils are lime- 

 hungry. The vegetation that has fallen upon them 

 and been buried in them has not changed to black 

 humus, or to very little of it. Why not! Because of 

 the absence of sufficient carbonate of lime. 



In Illinois one finds the northern end of the state 

 a black, rich prairie soil, very full indeed of humus. 

 The southern end of the state, on the other hand, 

 has a soil of light color, very deficient in humus. 

 Think what story this tells ! Glaciers ground up, 

 limestones in the northern end of the state and mixed 

 their detritus through the soil. Below the line whexe 

 the limestones reached the light colored soils begin. 



