34 Journal of Agricultural Research voi.xx.No. x 



observations do not deal directly with chlorosis, all are related to this 

 subject, since calcifugous plants are often chlorotic on calcareous soils 

 and since an exposition of the causes of chlorosis may afford an explana- 

 tion of the calcifugous character of some plants. 



There are a few plants which are very generally classed as calcifugous. 

 Among these are the following: Maritime pine (Pinus pinaster) (9) 

 chestnut (Castanea vesca), blueberry (Vaccinium), yellow and blue lupines 

 (Lupinus luteus and L. angustifolius) , certain species of sphagnum moss, 

 etc. Cases have been recorded, however, where some plants generally 

 considered calcifugous have been found growing on calcareous soils (7). 



Probably the unsuitability of calcareous soils for certain plants is due 

 not to carbonate of lime itself but to some soil characteristic usually 

 associated with carbonate of lime. This being so, calcifugous plants 

 might occur on certain calcareous soils provided some factor were oper- 

 ating to counteract the inhibiting characteristic usually associated with 

 carbonate of lime. 



Studies of chlorotic plants. — Besides the soil surveys of calcifugous 

 plants, there are several soil surveys which deal directly with the appear- 

 ance of chlorosis in cultivated plants. 



A case that has been the subject of much study is that of European 

 grapes grafted on certain American stocks. When these were introduced 

 on the calcareous soils of France and Germany they became chlorotic. 

 Several soil surveys and many observations prove that the chlorosis is 

 confined to calcareous soils and that there are varietal differences among 

 grapes with respect to their resistance to lime {22, 30, 33, 39 Viala and 

 Ravaz, 45). The accumulated data do not show, however, that all soils 

 containing more than a certain percentage of carbonate of lime produce 

 chlorosis in these varieties of grapes. 



The chlorosis and failure of chestnut trees on most soils containing 

 more than 3 per cent of carbonate of lime has been well established 

 through soil surveys and through observations by Fliche and Grandeau 

 (10), Piccioli (36), Vallot (44), and others. Vallot (44, p. 202) states 

 that Dr. Bonnet reported that the chestnut failed to grow in a calcareous 

 soil of Dijon, but when it was grafted on an oak it grew superbly. 



That yellow and blue lupines and serradella become chlorotic when 

 planted on calcareous soils is common knowledge in the calcareous 

 districts of France and Germany, 2 per cent of carbonate of lime usually 

 being sufficient to affect these plants. 



A soil survey in Porto Rico showed that a chlorosis of pineapples was 

 confined to the calcareous soils (12, p. 8-18). The only calcareous soils 

 not producing chlorotic pineapples on which data could be obtained were 

 some from the Florida Keys. These contained an exceptional amount of 

 organic matter. 



A chlorosis of sugar cane in Porto Rico was also found to be confined to 

 calcareous soils, although very many calcareous soils did not induce 



