4 2 



Journal of Agricultural Research 



Vol. XX, No. i 



chlorosis. Spraying with ferrous sulphate and adding ferrous sulphate 

 to the soil failed to increase the growth or improve the color of plants 

 growing in the soil containing calcium sulphate. That calcium sulphate 

 increased the amount of lime in the plants may be seen by the analyses 

 in Table V of plants 65 days old from experiment II. 



Table V. — Ash analyses of plants from experiment II 



It will be noted that the calcium sulphate increased the percentages 

 of lime and sulphur in the plant ash and diminished the percentage of 

 silicia but had little effect on the other constituents. 



The injurious effect of calcium sulphate on rice might have been due 

 to several causes. A large amount of gypsum evidently maintains a 

 solution more concentrated than that existing in any except alkali soils. 

 There is also the possibility of hydrogen sulphid being formed by bacteria 

 reducing sulphates. This occurred with soil preserved in a sample jar, 

 although such a result was not to be expected in what appeared to be a 

 normally aerated soil. The fact that calcium sulphate did not depress 

 growth in the clay soil lends credence to the view that the injurious 

 effect might have been that of a too concentrated soil solution. 



In order to make sure that an increased assimilation of lime is not a 

 cause of chlorosis, a test was conducted with lime salts applied to the 

 leaves. The results, given in experiments V and VI, to be described 

 further on, seemed to show definitely that an increased assimilation of 

 lime does not induce chlorosis. 



Although excessive quantities of various lime compounds seem to be 

 more or less injurious, each one appears to act differently; there is no 

 evidence of a general "lime effect" in inducing chlorosis. 



EFFECT OF AN ALKALINE REACTION IN INDUCING CHLOROSIS 



Pfeiffer and Blanck (55) in their first work on the intolerance of lupines 

 for calcareous soils concluded that lupines are especially sensitive to an 

 alkaline reaction and that the carbonate of lime not only depresses the 

 absorption of nutrients but is directly injurious to the roots of the plants. 

 While the alkaline reaction of carbonate of lime is evidently a factor in 

 the chlorosis, it is very evidently not directly injurious to roots of even 

 calcifugous plants. It was found in experiments with pineapple and 



