18 



diameter of the tube. In a tube 1 inch in diameter the water nses 

 V20 inch; in a tube '/lo in. diameter, the water rises J^ inch; in a 

 tube Vioo in. diameter, the water rises inches; and in a tube '/looo in- 

 diameter, the water will rise 54 inches. Now in a soil at rest 

 there are iine tubes or spaces between the soil grains themselves, 

 through which the water rises and passes into the air. After a hard 

 rain these tubes become smaller since the soil is closely packed, and in 

 this condition they are very effective in bringing up water. These 

 tubes bring up an enormous amount of water which is absolutely lost. 

 Now plowing or cultivating 2 or 3 inches deep breaks up these tubes 

 and prevents the escape of the water. 



Following is the result of an experiment to determine the effects 

 of cultivating on the moisture content of the soil, as reported by Snyder 

 in "Soils and Fertilizers": 



Per cent of water in corn field. 



with shallow surface "Without shallow surface 



cultivating cultivating 



Soil depth 3 to 9 inches 14.12 8.02 



Soil depth 9 to 15 inches 17.21 12.38 



Ordinarily one thinks of cultivation as a process for the purpose 

 of killing weeds and grasses, and therefore when these are killed 

 cultivating stops. But this is a great mistake and during dry spells, 

 cultivation should be kept up for the purpose of maintaining a cover- 

 ing of loose soil of 2 or 3 inches in order not to lose the little water 

 that you already have in the ground. This is especially needed after a 

 hard, packing shower. A hard shower of short duration may actually 

 do more harm than good during a drouth. The water does not enter 

 the soil to a sufficient depth to be of benefit to the roots, the sun dries 

 out the surface which becomes baked and cracked in consequence, and, 

 what is worse, they open up communication with the moisture already 

 in the soil, causing that to be drawn to the surface and lost. 



In an example mentioned by Snyder, tests, were made of the 

 amount of water in the soil before and after a shower, with the follow- 

 ing results: 



Per cent of water 



Surface soil i to 3 inches Subsoil 6 to 12 inches 



Before the shower 9.77 18.22 



After " " 22.11 16.70 



Gain.. 12.34 Loss . 1.52 



Now there was but enough watei' to raise the percentage in the 

 surface 11%, thorefoii; the 1.34% extra that it contained came from 

 the subsoil, which itself had lost one and a half per cent. ' This is just 

 what has happened in this neighborhood. The drouth began in January, 

 after a very heavy rainfall in December. At Santa Rita there have 

 been 20 weeks with showers from .04 in. to. 83 in These showers have 



