THE CONTROL OF SOIL MOISTURE 



281 



been intertilled. Not only has the surface been kept 

 well granulated, but the presence of optimum moisture 

 below has allowed the granulating agents to become 

 more active. The following of potatoes by corn is, at 

 least partially, an attempt to take advantage of the 

 better tilth of the soil with a crop that is particularly 

 benefited thereby. Again, a mulch not only tends to 

 allow a ready entrance of water into the soil, but at the 

 same time increases the water-holding capacity — factors 

 already emphasized in the discussion of control of losses 

 by percolation and run-off. By keeping down weeds * 

 another saving is effected, not only in moisture but also 

 in plant-food. Some results from an experiment 2 con- 

 ducted at Cornell University serve to illustrate the re- 

 lation of mulches and weeds to soil moisture and crop 

 production in a humid region in a season of good rainfall. 

 The crop grown was maize. Every third plot was a 

 check and was given normal treatment : — 



Check plot 



Weeds removed, but not cultivated . 



Mulched with straw 



Check plot 



No cultivation ; weeds allowed to grow 

 One cultivation ; weeds allowed to 



grow 



Check plot 



Yields Calcu- 

 lated to Basis 

 of 100 ON 

 Check Plots 



Soil Moisture 



during August 



Per Cent 



1 Cates, J. S., and Cox, H. R. The Weed Factor in the Culti- 

 vation of Corn. U. S. D. A., Bur. Plant Indus., Bui. 257. 1912. 



2 Craig, C. E. The Cause of Injury to Maize by Weeds. 

 Presented as a thesis for the degree of M. S. A., Cornell Uni- 

 versity. Unpublished. June, 1908. 



