8 



BULLETIN 499, U. S. DEPARTMENT OF AGRICULTURE. 



periods during the two seasons the wilting coefficient was nearly 

 reached. In other words, the trees in the check were wilted three times 

 during the two summer seasons, while the trees in the basins never 

 wilted. It will be seen from a comparison of sections C and D that 

 this wilting took place with available moisture in the fourth foot 

 of soil. 



Table I. — Average percentages of total and available soil moisture in the Sunny 

 Mountain grow, California, in 1914 and 1915. 



[Note. — A miner's inch of water flowing 24 hours will increase the moisture content of an acre of soil approx- 

 imately 1 per cent to a depth of 3 feet.] 



Soil treatment,' 1914. 







Before 





Before 



A fter irrigation. 



Before 



July 7. 



Aug. 1. 



irriga- 

 tion, 



Sept. 2. 



irriga- 

 tion, 







irriga- 

 tion, 











Aug. 15. 





Sept.21. 



Oct. 6. 



Nov. 4. 



Nov. 30. 



9.4 



12.2 



8.9 



12.9 



8.2 



15.2 



18.8 



11.1 



5.7 



7.7 



5.9 



8.9 



5.5 



11.3 



14.6 



6.5 



10.8 



11.3 



10.4 



9.9 



10.1 



11.9 



15.9 



11.0 



8.6 



9.1 



8.9 



9.2 



8.3 



7.9 



11.3 



7.9 



2.6 



3.2 



2.5 



6.2 



1.7 



8.5 



12.1 



4.7 



2.0 



1.0 



.6 



2.6 



-.6 



3.2 



8.4 



.6 



4.2 



4.2 



4.2 



3.4 



3.6 



5.2 



9.3 



4.8 



1.1 



2.4 



2.6 



2.5 



2.0 



2.5 



5.3 



1.8 



Aver- 

 age for 

 season. 



A .—Total in the first 3 feet: 



Mulched 



Cultivated 



B.— Total in the second 3 feet: 



Mulched 



Cultivated 



C. — Available in the first 3 

 feet: 



Mulched 



Cultivated 



D. — Available in the second 

 3 feet: 



Mulched 



Cultivated 



12.1 

 8.3 



11.3 

 7.7 



5.2 

 1.5 



4.9 

 2.5 





Dates of sampling before and after irrigation. 



CD 



Soil treatment,! 1915. 



< 



oToJ 

 ,o 



CD 



n 



Pi 



<< 



>r« 



3 

 < 



g 



■2 

 cd 



n 



l-s 



as 



"3 

 *-> 



>2 



n 



"3 



ha 

 CD 



to 

 < 



aTco 



CD 



3 



P. 



CD 

 03 . 



Sin 

 o 



o 

 O 



-pi 



M 



a? 



< 



a 

 O 



3 



CD 



m 



U 



o , 



a 



o 

 0) to 

 cm 



§ 



> 



A .—Total in the first 3 feet: 



8.8 

 7.2 



10.6 

 6.8 



2.7 

 1.8 



4.6 

 2.6 



17.8 

 15.1 



12.8 

 11.5 



10.9 

 9.1 



6.6 

 5.3 



9.5 



8.6 



10.4 

 10.0 



2.8 

 2.5 



3.8 

 3.3 



11.8 

 11.2 



12.2 

 10.3 



7.8 

 5.2 



6.0 

 4.6 



8.7 

 5.9 



10.0 

 9.6 



2.7 



.7 



4.9 

 3.8 



14.4 

 10.4 



11.5 



9.8 



7.8 

 3.8 



4.2 

 3.4 



9.4 



5.6 



11.0 

 9.0 



2.9 

 .5 



5.1 



4.8 



14.7 

 9.9 



11.5 

 9.0 



8.6 



4.4 



5.7 

 2.8 



9.1 

 5.0 



10.1 



7.4 



3.1 



-.6 



3.8 

 2.3 



13.9 

 10.9 



11.7 



8.7 



7.2 

 5.5 



5.8 

 2.8 



9.8 

 4.3 



10.4 

 7.3 



3.6 

 -1.2 



4.7 

 1.0 



11.6 



Cultivated 



8.6 



B— Total in the second 3 

 feet: 



11.1 





9.1 



C— Available in the first 3 

 feet: 

 Mulched 



5.4 



Cultivated 



2.9 



D. — Available in the second 

 3 feet: 



5.0 





3.3 







1 The mulched treatments were with basin irrigation; the cultivated, with furrow irrigation. 



SOIL-MOISTURE MEASUREMENTS IN BASINS, UNDER COVER 

 CROPS, AND UNDER A SOIL MULCH IN THE VIVIENDA GROVE. 



In the spring of 1915 a more extended series of experiments was 

 started in an orange grove on sandy loam soil in the Vivienda tract, 

 near Riverside. This soil is a little heavier than that of the Sunny 

 Mountain grove. 



