THE LIME-MAGNESIA RATIO 



99 



soils to pineapple chlorosis was studied. By means of pot ex- 

 periments and a chemical survey of the pineapple soils, the gen- 

 eral conclusion was arrived at that an excessive amount of cal- 

 cium carbonate in the soil was inducing chlorosis of pineapples. 

 It was found that even 2% of calcium carbonate renders an ordi- 

 nary sandy soil unfit for pineapples, but on the other hand that 

 soils may contain as much as 40% of calcium carbonate and still 

 grow good plants if the soil consists largely of organic matter. 

 Fertilizer applications were not successful in curing chlorosis, 

 but iron salts applied to leaves or crystals of ferrous sulphate 

 applied to the roots, were instrumental in bringing about normal 

 growth. Gile could find no support for the idea that either the 

 alkalinity of calcareous soils, or large quantities of assimilable 

 lime was the cause of the trouble, but rather believes that the 

 combination of the two which are responsible for the disturbance 

 in the mineral nutrition of the plant by preventing the assimi- 

 lation of iron, is responsible for the difficulty. A low iron con- 

 tent is always found in the ash and thus lends some support to 

 this view. Plants may show a high lime content in the ash, 

 yet may never have shown during their growth symptoms of 

 chlorosis. In brief, it would appear that these investigations 

 support the idea that an excessive amount of lime, when made 

 soluble and therefore assimilable by the roots of pineapples, like 

 excessive amounts of other soluble materials, may seriously in- 

 terfere with growth, but these investigations do not show that 

 any relationship is evident here between the bad plant condition 

 and the need of a proper lime-magnesia ratio. 



In the second paper"*" a discussion of other experiments is 

 given in which rice is the crop plant employed. The rice was 

 grown in culture solutions for forty and fifty days. Varying 

 amounts of calcium chloride and magnesium chloride were added 

 to the nutrient solution. These were used in a large variety of 

 ratios in order to discover if possible if a certain ratio was most 

 favorable to the growth of rice. An attempt was also made to 

 study, besides this one question, that of the concentration of 

 the solution in its relationship with the growth of the rice plants. 



*° Bui. 12, Porto Rico Sta., 1913. 





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