26 University of California Publications in Agricultural Sciences [Vol.3 



field work cannot be given in this paper but will need discussion 

 separately elsewhere at some future time. The experiment proper, 

 however, has now been in operation for more than two years and the 

 results obtained have been so interesting as to more than justify their 

 presentation and discussion here. 



Plan of the Experiment 



It was decided to grow the young lemon trees in galvanized iron 

 cylinders, 24 inches in depth and 15 inches in diameter. The cylin- 

 ders were painted with a heavy coating of asphalt. The soil used in 

 them is a loam having the following mechanical analysis (Bureau of 

 Soils method), which was furnished us through the courtesy of 

 Professor C. F. Shaw: 



First foot Second foot Third foot 



Fine gravel 1.45 1.14 1.71 



Coarse sand 3.24 3.13 4.27 



Medium sand 3.32 3.25 4.13 



Fine sand 12.77 12.33 12.58 



Very fine sand 42.99 44.93 43.22 



Silt 18.74 19.31 16.61 



Clay 17.49 15.91 17.48 



On the basis of this mechanical analysis the Bureau of Soils would 

 classify the soil as a fine sandy loam, but owing to its relatively high 

 clay and silt content it should, in the junior author's opinion, be 

 classified as a light clay loam, but certainly as no less than a loam. 

 Mr. Chas. A. Jensen of the Bureau of Plant Industry, United States 

 Department of Agriculture, was good enough to furnish the ' ' moisture 

 equivalents" and "wilting coefficients" of the first three feet in depth 

 of the soil used, as it occurs under field conditions. Mr. Jensen's 

 determinations follow : 



Wilting per cent Moisture equivalent 



First foot 9.3 17.0 



Second foot 8.7 15.9 



Third foot 8.1 14.0 



The soil used in the cylinders was obtained from a lemon orchard 

 now twenty-three years of age in which the trees have always shown 

 good vigor and high productivity. The soil from the first and second 

 feet in depth was thoroughly mixed in preparation for use in the 

 cylinders. The same amount of soil was weighed into every cylinder. 



The variety of lemons selected for the test was the Lisbon. The 

 trees were one year old and as nearly uniform as could be obtained. 



