CONTENTS 



Xlll 



§ 180 ; Movement of soil air, § 181 ; Movement of 

 water, § 182 ; Diffusion of gases, § 183 ; Composi- 

 tion of soil air, § 184 ; Production of carbon dioxide 

 in soils, § 185 ; Conditions that affect the quantity 

 of carbon dioxide in soils, § 186 ; Usefulness of air in 

 soils, § 187; Oxygen, § 188; Nitrogen, § 189; Car- 

 bon dioxide, § 190 ; Control of the volume and move- 

 ment of soil air, § 191; Soil temperature, § 192; 

 Sources of soil heat, § 193 ; Relation of soil tempera- 

 ture to atmospheric temperature, § 194 ; Factors that 

 modify soil temperature, § 195 ; Control of soil tem- 

 perature, § 196. 



Questions on Chapter X ...... 



Laboratory Exercises ....... 



Movement of soil air as measured by texture and 

 structure, I ; The presence of carbon dioxide in soil 

 air, II ; Production of carbon dioxide by germs, III ; 

 Temperature and soil color, IV ; Slope and soil tem- 

 perature, V; Drainage and temperature, VI. 



152 

 152-154 



CHAPTER XI 



Nitrogenous Fertilizers 



Relative quantities of the different forms of nitro- 

 gen in soils, § 197 ; Forms in which nitrogen is ab- 

 sorbed by plants, § 198 ; Nitrates as plant-food 

 materials, § 199; Absorption of ammonia by agri- 

 cultural plants, § 200 ; Direct utilization of organic 

 nitrogen by crops, § 201 ; Forms of nitrogen in fer- 

 tilizers, § 202 ; Nitrate of soda, § 203 ; Crops mark- 

 edly benefited, § 204 ; Effect of nitrate of soda on soils, 

 § 205 ; Sulfate of ammonia, § 206 ; Composition of 

 sulfate of ammonia, § 207 ; Action when applied to 

 soils, § 208; Cyanamid, § 209; Composition of 

 cyanamid, § 210; Changes in the soil, § 211; Fer- 

 tilizers containing organic nitrogen, § 212; Vege- 

 table products, § 213; Animal products, § 214; Fish 

 waste, § 215; Guano, § 216; Effects of nitrogen on 

 plant growth, § 217 ; Availability of nitrogenous 



155-168 



