32 



Campbell's 1902 Soil Culture Manual. 



POUNDS OF WATER PER CUBIC FEET OF WET AREA. 



1st foot. 2nd foot. 3d foot. 4th foot. 



Before wetting 11.78 15.79 14.73 14.03 



After wetting 14.06 17.52 15.58 15.40 



Gain 2.28 1.73 .85 1.43 



POUNDS OF WATER PER CUBIC FOOT OF AREA NOT WET. 



1st foot. 2nd foot. 3d foot. 4th foot. 



First samples 12.38 17.05 14.92 14.48 



Second samples 12.75 17.72 15.40 14.17 



Gain 37 .67 .48 .31 



Now it will be seen from these results that the water contents of 

 the soil increased on both areas, but at the rate of 6.23 pounds to the 



square foot on the portion wet, and 1.21 pounds on the portion not wet. 

 The nineteen hours which intervened between the taking of the two sets 

 of samples was a period of very little evaporation, most of it being in the 

 night, and the following morning was cloudy and very damp and the re- 

 sult was that capillarity gave to the area not wet 1.21 pounds more water 

 per square foot than it lost by evaporation, but the wet area had gained 

 6.23 pounds and yet only 1}?^ pounds had been added to the surface, mak- 

 ing the increase by capillarity 6.23-1.33=^4.90 lbs., and if we subtract from 

 this the amount which the controlling area gained we shall have 3.69 

 pounds as the water gained due to the wetting of the surface, or 453^ tons, 

 or nearly half inch of rain per acre. We mention this to show the remarka- 

 ble effect of these simple conditions on the changing of location or move- 

 ment of moisture in the soil. It will be seen from Prof. King's statement 

 that if we allow the evaporation of our surface soil to such an extent as to 

 dry to some depth it is then more difficult for the moisture to rise up from 

 below to feed the plant; or in other words it moves much slower, thus 

 showing the importance of watching the conditions very closely. 

 If there should be such a remarkable effect upon the soil one. two, three, 

 and four feet below the surface by simply slightly wetting the surface 

 what may we expect from the effect of a slight rain upon our moisture just 

 beneath the mulch. This shows the very great importance of cultivating 

 as quickly as possible after such rains. If the reader will observe and con- 

 sider closely the last few remarks he will readily see that by simply shal- 

 low cultivation, even though more frequent, and later cultivation, it is still 

 possible to have come far short of accomplishing the best possible results. 

 It is these little quite important points that the average farmer does- not in 

 the least comprehend that we have frequently referred to that often causes 

 trouble sometimes quite serious. 



In closing this chapter we venture to repeat that we may emphasize 

 some things taught. 



