Plates 4 and 5 (next two pages). — Plot 23. 

 Alfalfa, no treatment.— Plot 24. Alfalfa, sulphur 

 plot. — An experiment in the field demonstrating 

 reclamation of a black alkali soil. In this case 

 sulphur was used to provide acid by oxidation to 

 liberate Ca ions from carbonates and displace so- 

 dium ions held by soil colloids. Other methods have 

 also been employed successfully. (See discussion 

 by Kelley in Calif. Agr. Exp. Sta. Bulletin 617). 

 (From W. P. Kelley, 1937). 



