ILLUSTRATIONS xi 



87. A . Showing Angular Character of Quartz Particles in Decomposed 



Gneiss. B. Quartz Granules from Beach Sand. C. Showing 

 Outlines of Shreds of Volcanic Dust as Seen Under Microscope . 179, 180 



88. Diagram Showing the Arrangement of Soil Particles 180 



89. The Annual Rainfall Over the United States 190 



90. Soil Particles Showing Films and Waists of Capillary Water 200 



91. Large and Small Bubble Connected by a Tube 200 



92. Showing Theoretically the Thickness of Films in a Vertical Soil 



Column 201 



93. Showing the Effect of Various Amounts of Organic Matter on the 



Rise of Capillary Water from a Free- water Surface for a 14-day 

 Period 208 



94. Diagram Showing the Relation of Different Forms of Moisture to the 



Available and Unavailable Moisture of Soils 214 



95. The Difference in Germination and Growth on Undrained und 



Drained Soil 223 



96. Pipe Heaved Nearly G Inches During Winter of 1915-1916 225 



97. Alfalfa that was Completely Killed by Heaving 226 



98. The Obstructions Interfere with the Current and Cause Deflections. . 227 



99. Ditch Gradually Being Filled by Soil Due to Current Being Retarded 



by Grass 227 



100. A Neglected Ditch Often Seen in Heavily Wooded Areas 227 



101. Showing the Water Table with Lines of Tile Soon After the Insertion 



of Another Line 228 



102. A Good Method of Conserving Moisture 234 



103. Types of Rainfall Over Dry-farm Area of the United States 239 



104. Sage Brush on Land Well Adapted to Dry Farming. Utah 239 



105. A Gravelly Soil Not Well Adapted to Dry Farming 240 



106. A Deep, Medium-grained Soil Well Adapted to Dry Farming. Utah . 243 



107. Campbell Subsurface Packer 247 



108. Turkey Red Fall Wheat, Without Irrigation, Yield 58 Bushels Per 



Acre .' 249 



109. White Hulless Barley on Land Continuously Cropped 249 



110. White Hulless Barley on Land Fallowed the Previous Year 249 



111. Corn Grown on Dry-land Farm. Utah 252 



112. Dry-farm Potatoes. Utah 253 



113. Conduit for Conducting Water to Where it May be Used for 



Irrigation 258 



114. Concrete-lined Canal that Permits no Loss by Seepage 258 



115. Roosevelt Dam, Salt River, Arizona 260 



116. Granite Reef Diversion Dam, Salt River Project. Arizona 260 



117. Desert Lands and Homestead, Huntloy Project, Montana 261 



118. Wheat Field, Minidoka Project, Idaho' .201 



119. Chains for Puddling the Mud of Canals to Prevent Set-page 267 



120. Rectangular Weir 268 



121. Trapezoidal or Cippoletti Weir, Showing Method of Dividing the 



Stream 269 



122. Basin or Check System of Irrigating Orchards 270 



123. Irrigating Potatoes by Furrows .271 



124. Method of Irrigating by Overhead Sprays 



125. Mallin Ranch, Salt River Project, Arizona. . 



126. Alfalfa Field, Yuma Project, Arizona '. 274 



127. Beginning of an Alkali Sjx>t . . 



128. Alkali Area Showing the Absence of Vegetation. 



129. Apricot Trees. The Scanty Foliage Shows the Kffoct of Alkali. . . 283 



130. An Orchard Well Cultivated Prevents the Rise of Alkali 286 



