EXPERIMENT STATION BULLETINS. 443 



For each square foot of horizontal area and to a depth of three feet, Plot 

 1 had 37.70 pounds of water; Plot 2, 40.41 pounds, and Plot 3, 39.86. 



It may seem that the differences in moisture content as shown in the 

 table are not large enough to be of practical importance; there is but an 

 increase of 5.S3 per cent in Plot 3 and 7.26 per cent in Plot 2 over the un- 

 cultivated plot. It must be remembered, however, that not all of the water 

 that a soil contains is available for crop production. According to King, 

 (Wis. Keport 1893, page 178) growth ceases on a sandy soil when it con- 

 tains but 6 f c of moisture and on a clay soil when it contains but 9 $. The 

 soil on which this experiment was tried was a loam intermediate between 

 sand and clay and would retain probably 7.5 i unavailable moisture. For 

 the upper three feet this would be 21.3 pounds of water per square foot of 

 horizontal area. According to this calculation the amount of water in 

 each plot to a depth of three feet for each square foot of area available to 

 plants would be: Plot 1, 16.4 pounds. Plot 2, 19.11 pounds and Plot 3, 

 18.56 pounds. Using the available moisture of Plot 1 as a basis we have in 

 Plot 2, 16.52 per cent and in Plot 3, 13.17 $ more available moisture than 

 in Plot 1. 



As no weeds were allowed to attain any considerable size on these plots, 

 one great loss of moisture on ordinary uncultivated land was entirely 

 obviated. Again, all the plots had thorough cultivation until the begin- 

 ning of the experiment, June 25th. When these facts are considered it is 

 significant that so much more moisture was found in the cultivated plots 

 than in the uncultivated that of the plot receiving ordinary cultivation 

 being especially noteworthy. 



The size of the crop depends very largely upon the water supply. In 

 moist years, where the rainfall is ample and well distributed through the 

 season, the corn crop is large whether the cultivation is attended to or not. 

 It is in the dry year that the skill of the farmer reaps its reward. By 

 cultivation at the right times, to the proper depth and with the proper 

 implements he is able to hold the rainfall, prevent its escape and utilize 

 it in the maturing of a crop which would otherwise be a comparative fail- 

 ure. The profit on a corn crop often hinges on the presence of the last 

 per cent of available moisture and the efforts of the farmer are directed to- 

 wards its conservation. 



Diagram No. 1 will show the variations in the per cent of water in the 

 top foot of each plot throughout the season. The effects of rains and of 

 excessively dry weather should be noted. The latter is shown by the line 

 marked relative humidity, the lower this line the drier the atmosphere. 



Diagram No. 2 shows the average per cent of moisture to a depth of 

 three feet in each of the plots. Perhaps the most striking feature of this 

 diagram is the absence of excessive variation in the amount of moisture 

 in Plot 2. On this point Prof. Milton Whitney writes in the Year Book 

 of the Department of Agriculture for 1895, page 124, " Water is thus con- 

 served for the use of crops and the supply is more abundant and more 

 uniform than it would have been without cultivation," also: "A soil 

 with a compact surface quickly dries out and the water supply fluctuates 

 rapidly and excessively to the detriment of most crops during the grow- 

 ing period." 



