12 BULLETIN" 499, U. S. DEPARTMENT OF AGRICULTURE. 



Table IV. — Average total percentages of soil moisture to a depth of 3 feet in 



I In Victoria urore. Villi font id, ill 1915. 



[Note.— Tlio first four treatments were not irrigated between April 22 and Juno 10. The last six 

 fcreal naenta were irrigated on May 20.] 



Soil treatment. 



Alfalfa: 



In basins 



Same, plus lime. 

 Manure: 



In basins 



Same, plus lime 

 Sweet clover: 



Cover crop 



Same, plus lime. 

 Barley: 



Cover crop 



Same, plus lime. 



Uncultivated 



Same, plus lime 



Dates of sampling before and after irrigation. 



After, 

 Apr. 

 22. 



17.2 

 17.9 



10.4 

 17.7 



Bofore, 

 June 



10. 



12.8 

 12.5 



8.9 

 9.9 



13.4 

 13.1 



11.3 



11.0 

 14.5 

 13.4 



After, 



June 



22. 



14.5 

 15.7 



13.1 

 12.9 



14.6 

 17.6 



10.4 

 10.2 

 14.3 

 11.6 



Beforo, 



July 



12. 



10.6 

 11.1 



9.2 

 10.1 



7.0 

 8.0 



7.4 

 5.9 

 9.0 

 9.3 



A ft or, 

 Julv 

 26. 



15. 

 18.4 



17.8 

 17.7 



10.5 

 10.2 



0) 



( l ) 



9.6 

 11.9 



Bofore, 

 Aug. 



11.9 

 11.7 



11.8 

 12.0 



5.3 

 5.3 



6.3 

 8.2 



After, 



Aug. 



25. 



15.7 

 17.7 



17.4 

 16. 9 



(») 



15.3 

 13.7 



Before, 



Sept. 



13. 



10. 5 



12.0 



10.3 

 11.1 



8.0 

 9.8 



After, 



Sept. 



17. 



14.5 

 17.5 



17.1 

 19. 9 



Bofore, 

 Oct. 

 12. 



11.1 

 12.5 



11.9 

 12.8 



i Basined. 



It is apparent from Table IV that the greatest reduction in mois- 

 ture took place under the cover crops, the loss being greater than 

 from the uncultivated row. This is brought out more clearly in 

 Table V, which gives the amount of available moisture in the sur- 

 face 3 feet of soil before irrigation, the critical moisture period. 

 This table shows that the mulched-basin system is the only one that 

 retained available moisture at all times. In all the other treatments 

 the moisture content at some time during the summer was reduced 

 below the wilting coefficient. This deficiency in the moisture supply 

 in the case of the cover-crop tests was also shown by the appearance 

 of the trees, which wilted badly during the summer before the 

 irrigation periods came around. 



Table V. — Average percentages of available soil moisture to a depth of 3 feet, 

 before and after monthly irrigations, in the Victoria grove, California, in 

 1915. 



Soil treatments. 



Before monthly irrigations. 



June 

 10.i 



July 

 12. 



Aug. 

 13. 



Sept. 

 13. 



Oct. 

 12. 



Aver- 



After monthly irrigations. 



Apr. 

 22. 



June 

 22. 



July 

 26. 



Aug. 

 25. 



Sept. 

 17. 



Alfalfa: 



In basins 



Same, plus lime 

 Manure: 



In basins 



Same, plus lime 

 Sweet clover: 



Cover crop 



Same, plus lime 

 Barley: 



Cover crop 



Same, plus4ime 



Uncultivated 



Same, plus lime 



4.7 

 4.4 



5.0 



4.5 



3.3 



3.4 

 5.8 

 4.3 



2.2 

 2.9 



-1.0 

 - .4 



-2.6 

 .4 

 .6 



3.1 

 3.3 



3.1 

 2.8 



-2.4 

 -3.0 



( 2 ) 

 ( 2 ) 

 -2.0 



.7 



1.8 

 3.8 



1.5 

 2.0 



( 2 ) 

 ( 2 ) 



2.2 

 4.1 



3.2 

 3.3 



- .7 

 .9 



( 2 ) 

 (?) 



2.8 

 3.7 



1.8 

 2.0 



.5 



.4 



1.3 

 .4 

 .9 



1.6 



7.8 

 9.0 



6.5 

 8.0 



5.7 

 7.4 



4.2 

 3.5 



6.2 

 8.9 



2.2 

 1.4 



5.7 

 2.4 



6.2 

 9.7 



8.5 

 8.0 



1.9 

 1.5 



( 2 ) 

 ( 2 ) 

 1.1 

 3.0 



7.4 

 9.7 



9.1 



8.1 



( 2 ) 

 ( 2 ) 



6.7 

 5.1 



5.8 

 9.0 



8.3 

 10.4 



( 2 ) 

 ( 2 ) 



1 The last previous irrigation of basins was given on April 22; other treatments about May 20. 



2 Basined. 



