Transpiration as a Factor in Crop Production. 9 
TABLE PAGE 
47. Evaporation from free water surfaces 36 square 
inches in area at four elevations in a spring wheat 
field. 1912 122 
48. Weekly summary of evaporation from free water 
surfaces 36 square inches in area at four elevations 
in an oat field. 1913 . 122 
49. Weekly summary of evaporation from free water 
surfaces 36 square inches in area at four elevations 
in an oat field. Evaporation expressed as percent- 
age of evaporation from the upper jar. 1913 123 
50. Summary showing relative free water evaporation 
rates at different elevations in corn and small- 
grain fields. 1912-1914 123 
51. Summary showing the relative responsiveness of free 
water surface evaporation from several styles of 
evaporation jars having 36 square inches of 
surface area 126 
52. Various ways of expressing water content of soil in 
different degrees of saturation, during three years — 
1910, 1913, and 1914 128 
53. Growth relationships and water requirements of 
corn in five different degrees of soil moisture. 1910 . . . 133 
54. Growth relationships and water requirements of 
corn in three different degrees of soil moisture. 
1913 134 
55. Growth relationships and water requirements of corn 
in four different degrees of soil moisture, with and 
without manure. 1914 135 
56. Summary showing the growth relationships and water 
requirements of corn in different degrees of soil 
moisture, during three years. 1910, 1913, and 1914 . . . 137 
57. Summary of three years' results with different degrees 
of soil-moisture content. 1910, 1913, and 1914 138 
58. Summary of three years' results with different degrees 
of soil-moisture content. 1910, 1913, and 1914 139 
59. Summary of average analyses of soils used in filling 
the potometers in the soil fertility series in 1911 and 
1914 144 
60. Total amount in pounds of nitrogen, acid soluble 
potash and phosphoric acid contained in the soil 
of the average potometer in each group of the 
fertility series. 1911 and 1914 145 
61. Summary of data secured from potometers contain- 
ing soils of six degrees of fertility. 1911 147 
