INDEX 



525 



PAGE 



Percolation 164 



Percolation of water, factors affect- 

 ing 167 



Direction of 168 



King's figures on 166 



Prevention of 191 



Relation to climate 193 



Rothamsted figures on 192 



Phosphate fertilizers 334 



Physical agencies of rock decay . . 14 



Absorption 102 



Character of soil, relation to irri- 

 gation 224 



Chief groups of soil 66 



Effects of organic matter 129 



Of arid and humid soil 64, 79 



Of soil 68 



Processes in soil, relative to tem- 

 perature 431 



Properties of soil-forming miner- 

 als 6,7 



Properties of soil most suited to 



irrigation 237 



Piedmont soils 40 



Planker, drag or float, efficiency of .4S9 



Plants amount of water used by . . 133 



And animals, agencies in rock 



decay 28 



Plant food, elements of 3, 291 



As factor in growth 1 



Derived from rocks 3 



Derived from air and water. ... 3 



Diseases, effect of lime 350 



Elements, abundance of 4 



Elements in soil, abundance. 6S, 282 



E xhaustion of 285 



Groups of 3 



In the soil, amounts removed by 



crops 281 



Relation to crop rotations 509 



Plant growth, factors in 1 



Influence of soil temperature on 449 

 Plants, injured by gravitational 



water 163 



Micro-organisms in the soil 392 



Physiological requirements in 



adaptation 499 



Requirements for growth 1 



Result of the inherent capacity 



of seed 1 



Result of environment 1 



Roots, effect on the soil 391 



Roots, effect on soil structure . . .113 



PAGE 



Plants, roots, importance of ad- 

 vance through soil 174 



Roots, strike deep in drained 



soil 245 



[/Plasticity, cause of 97 



Of humus 129 



Properties of 97 



Plows, types of 471 



Attachments for uses 476 



Efficiency of depends on 470 



Effect on soil structure Ill 



Hillside 475 



Mode of action 469 



Moldboard, adaptation to soil. .471 

 Relation of use to soil moisture. 470 



Subsoil 477 



Plowing deep, advantages of 218 



Relation to humus supply . . . .218 



Plow-land, mulching 209 



Plow-sole, character of 474 



Pore space in soil 93 



Diameter of individual 94 



Porosity of rocks 21 



Affected by moisture 162 



Calculation of 92 



Of soil 92 



Potassium fertilizers 340 



Potato growing, straw mulches in . 202 



Harvester, as cultivator 486 



Potts, figures on heat conductivity 



of soil 459 



Poult ry manure 372 



Practices used in soil management .465 

 ' Practices in soil management, pri- 

 mary and secondary functions 



of 465 



Pressure of air, effect on percola- 

 tion 168 



Primary minerals 5 



Process of atmospheric rock decay . 16 



Productiveness of soil depends on . 36 



In relation to crop rotations. . . .503 



Properties of soil 68 



Properties of soil separates 80 



Puddled structure 90 



Puddled soil, changed by lime. ... 117 



Danger from subsoilins 478 



Movement of water in 182 



Pulverization, action of plow in. . .469 

 Putrefaction 408 



Quinke estimates molecular attrac- 

 tion 146 



