XX 



LIST OF ILLUSTRATIONS 



NO. PAKE 



27. Alway's experiment, showing relation between crop and soil- 



moisture 96 



28. Water in small tubes 104 



29. How rainwater is changed to capillary soil- water . . .110 



30. Soil-water in fall and in spring 115 



31. Kubanka wheat field in Montana ...... 117 



32. Annual rainfall and evaporation compared .... 131 



33. Checked land 142 



34. Alfalfa in cultivated rows 151 



35. The effect of cultivation 154 



36. Flax in Montana 156 



37. Plowing in the N'orthwest 161 



38. Root-hairs and soil particles 167 



39. Penetration of root-hairs through soil ..... 169 



40. Wheat roots with soil particles 171 



41. Stomata 173 



42. Photograph of stomata ........ 173 



43. Ideal tilth of soil 181 



44. Interior of olive orchard in Sfax, Tunis .... 184 



45. Winter wheat in Wyoming ....... 189 



46. Dry-farm potatoes, Montana 190 



47. Clean summer fallow . 196 



48. Barley on land continuously cropped 199 



49. Barley on summer fallowed land 201 



50. Combined harvester and thresher, Montana .... 211 



51. Header at work, Washington 213 



52. Cultivating oats with weeder, Wyoming . . . . 219 



53. Header at work 229 



54. Oat field, Utah 231 



55. Winter wheat and alfalfa, Wyoming ..... 235 



56. Turkey wheat field, Montana 239 



57. Barley field, Nevada 242 



58. Corn field. New Mexico 246 



59. Oat field, Montana . 250 



60. Ears of corn, Montana 255 



61. Heads of macaroni wheat 259 



62. Heads of hard winter wheats 265 



63. Milo maize field, Montana 266 



