498 University of California Publications in Agricultural Sciences [Vol. 1 



TABLE I 



Chemical Analyses of Soils Used 



Greenhouse 



humns clay Clay 



adobe adobe 



Insoluble residue 74.03 85.50 



Soluble silica 9.18 7.40 



Lime (CaO) 2.26 1.05 



Iron Oxide (FeSOj) 4.59 3.61 



Aluminum oxide (ALO3) 5.80 3.85 



Sulfuric acid (SO3) 



Manganese sesqui-oxide (Mn304) .13 .13 



MagTiesium oxide (MgO) .72 .54 



Potash (K.O) 62 .25 



Soda (Na.O) 43 .21 



Phosphoric acid (PA) 48 .20 



Moisture and volatile matter 11.68 4.70 



Total 100.78 100.44 



Nitrogen 31 .12 



Humus 3.20 1.85 



Nitrogen in humus 6.75 8.00 



Oakley 

 sand 



92.04 



3.14 



.66 



3.60 



1.24 



Trace 

 .22 

 .30 

 .17 

 .16 

 1.72 



100.32 

 .03 

 .30 



11.80 



thoroughly as possible to approach closely a uniform distribution 

 of the salt. Obviously such thorough mixing as could be desired 

 was not attained with the PbSO^ ; hence one reason for the 

 irregularity of some of the results obtained therewith. In the case 

 of the copper, lead, manganese and zinc sulfates the treatments 

 were made as parts per million of the dry weight of the soil, 

 whereas the ferrous sulfate was supplied in much larger quan- 

 tities on the percentage basis. The precise quantities of the salts 

 employed are shown in the tables submitted below, but it is 

 added here, in explanation, that the treatments as indicated there 

 represent aggregate amounts in the case of the copper, zinc, iron, 

 and potash alum series of two separate applications, one prior 

 to planting the first and the other prior to planting the second 

 crop of barley in the humus clay adobe soil. It will further be 

 noted that all the salts were added in the form of sulfates of 

 the metals studied, except as otherwise stated. 



Water was applied to the surface of the soil in irrigating. 

 As a rule, that operation was carried out twice a week, or as 

 needed, and 400 c.c. of tap water was the amount used at every 

 irrigation. From earlier tests it appeared that this quantity of 



