Oct. i, 1920 



Cause of Lime-Induced Chlorosis 



41 



Table III. — Influence of spraying with ferrous sulphate on the depressing effect of gypsum 



The plants in the soil to which gypsum had been added were markedly 

 behind the others in growth from the start, and they were at times of 

 poorer color, though they were never typically chlorotic. Plants in soil 

 without gypsum were of good color at all times. No effect from spraying 

 with ferrous sulphate was observable. 



Experiment IV. — A further experiment with gypsum and ferrous 

 sulphate was conducted in pots in a glass house. Six rice plants per pot 

 were grown from July 7 to October 25, 191 3. Each pot contained 37 

 pounds of sandy soil, to which 13 gm. ammonium sulphate, 11 gm. acid 

 potassium phosphate, and 3.6 gm. sulphate of potash were applied. 

 The moisture content of the soil was maintained at the optimum. The 

 results appear in Table IV. 



Table IV. — Influence of different treatments with ferrous sulphate on the depressing 



effect of gypsum 



The color of the plants grown in the soil to which gypsum was added 

 was as good as that of the controls up to the eighty-fifth day, but from 

 the eighty-fifth to the one hundred and tenth day the former were yellow. 

 The controls were always of a good green color. No effect from either 

 of the treatments with ferrous sulphate was observable. 



Summary. — In all the tests, except that with the clay soil, calcium sul- 

 phate depressed the growth of rice and induced a certain amount of 

 yellowing. The yellowing, however, was not that typical of lime-induced 



