52 FUNDAMENTALS OF FRUIT PRODUCTION 



Table 29. — Rate of Percolation of Water Through Clay Loam Soil'" 



Inches 



of 

 rain- 

 fall 



Inches of water drained 

 through soil columns 



Per cent, of rainfall per- 

 colating through soil 

 column 



20 40 



inches inches 

 deep deep 



inches 

 deep 



60 

 Inches 

 deep 



January . . . 

 Februarj' . . 



March 



April 



May 



June 



July 



August . . . . 

 September 

 October. . . 

 November 

 December. 



2.32 

 1.97 

 1.85 

 1.89 

 2.11 

 2.36 

 2.73 

 2.67 

 2.52 

 3.20 

 2.86 

 2.52 



1.82 

 1.42 

 0.87 

 0.50 

 0.49 

 0.63 

 0.69 

 0.62 

 0.88 

 1.85 

 2.11 

 2.02 



2.05 

 1.57 

 1.02 

 0.57 

 0.55 

 0.65 

 0.70 

 0.62 

 0.83 

 1.84 

 2.18 

 2.15 



1.96 

 1.48 

 0.95 

 0.53 

 0.50 

 0.62 

 0.65 

 0.58 

 0.76 

 1.68 

 2.04 

 2.04 



78.5 

 72.2 

 47.6 

 26.5 

 23.2 

 24.0 

 25.3 

 23.2 

 35.0 

 57.8 

 76.7 

 80.3 



88.4 

 80.0 

 55.6 

 30.0 

 26.1 

 27.6 

 25.6 

 23.2 

 32.8 

 57.5 

 76.3 

 85.4 



84.5 

 75.2 

 52.0 

 28.0 

 23.6 

 26.3 

 23.8 

 21.7 

 30.0 

 52.3 

 72.4 

 81.0 



Mean total per year. 



28.98 



13.90 



14.73 



13.79 



48.2 



51.0 



48.0 



Results for: 

 Maximum rainfall. 

 Minimum rainfall. 



38.70 

 20.50 



23.50 



7.32 



23.60 

 7.90 



24.30 



7.70 



60.7 

 35.7 



61.0 



38.5 



63.0 

 37.6 



generally necessary to use more water than in heavy soils under similar 

 climatic conditions and with the same fruits. The extra amount of 

 water required by such soils may be reduced somewhat by lighter and 

 more frequent applications, but this too may be carried to an extreme and 

 result in an unnecessary waste through evaporation. An illustration of 

 this principle is furnished by certain orchards on the Umatilla Irrigation 

 Project in eastern Oregon. Many orchards on this project have required 

 7 or 8 acre-feet of water in order to bring a crop of fruit to maturity, 

 though the trees themselves could use only 9 or 10 inches. Evaporation 

 rates in the climate of that section are very high, but the main reason 

 for applying 9 to 10 times more than the trees actually use is the extremely 

 high percolation through light porous sandy soils and subsoils. 



The Rise Of Water By Capillarity. —It is often thought that much of 

 the water that percolates through the soil again rises by capillary action 

 and becomes available to the trees later in the season. Investigations 

 of recent years tend to minimize the importance of this upward movement 

 of soil moisture. The generally accepted opinion of the present may be 

 summarized in the following statement by Rotmistrov;!"^ "As regards 



