Xll 



CONTENTS 



The temperature of the soil .... 



How warm the soil must be for various crops 



The comparative temperature of different soils 



Drainage promotes warmth 



Influence of the exposure on the warmth of soils 



Dark colored soils absorb more heat 

 , The influence of tillage on soil temperature 

 The ventilation of the soil .... 



The necessity for air in the soil 



Methods of improving the ventilation of soil 

 Electricity in the soil 

 Germ life in the soil ..... 



The beneficial work of nitrogen-fixing germs 



Conditions essential to the life of these germs 



Germs that waste nitrogen 



A multitude of other soil bacteria . . 

 Chemical changes in the soil .... 



PAGB 



31 

 81 

 32 

 33 

 34 

 34 

 36 

 37 

 37 

 37 

 39 

 40 

 40 

 42 

 42 

 43 

 44 



CHAPTER III. THE KINDS OF SOILS AND HOW TO 

 MANAGE THEM 



Sedentary soils 



Transported soils 

 Alluvial soils 

 Drift soils 

 Wind-built soils 



The composition of soils 

 The basis of separation 

 The characteristics of sand 

 The characteristics of clay 

 The characteristics of silt . 

 The characteristics of humus 



The leading types of farm soils 



Sandy soils 



Sandy loams . 



Clay soils 



Clay loams 



Loams 



Gravelly and stony loams 



Peat and muck 



Loess soils 



Adobe soils 



Salt marsh soils 



46 



47 

 47 

 48 

 50 

 51 

 51 

 51 

 52 

 52 

 53 

 53 

 54 

 55 

 56 

 58 

 59 

 59 

 60 

 62 

 63 

 64 



