THE LIME-MAGNESIA RATIO 121 



Loew and Honda, ^^ in making a study of the lime and mag- 

 nesia requirements of conifer trees, tested Cryptomeria japonica, 

 Thuja obtusa and Pinus densiflora. Lime is considered, as a 

 result of these experiments, to be best for such trees, while mag- 

 nesian soils are relatively poor for them. The intrinsic value of 

 lime in the soil for these plants is claimed to be shown even when 

 it is much surpassed in quantity by the magnesia. The lime in 

 the soil manifests its presence by the production of greatly short- 

 ened leaves. 



Soon after the appearance of this work there was published by 

 R. Heinrich" an essay on marl and marling which received a 

 prize. Of immediate interest to us in this paper is one fact men- 

 tioned by Heinrich, namely, that of a series of substances tried 

 on lupines, magnesium carbonate proved the most injurious in 

 that 0.5% of magnesium carbonate completely checked the 

 growth of plants. 



Like^^'ise Passerini*^" found that magnesium carbonate, applied 

 at the rate of two to five hundred kilograms per hectar reduced 

 the yield of wheat and injured its quality. 



Bearing more directly on the question of the action of differ- 

 ent compounds of calcium and magnesium on plants D. Meyer •^^ 

 carried out a series of experiments in pots of 6,000 grams capacity. 

 Sand and peat and sand loess were used in these pots. Oats, 

 potatoes, horse beans, vetch, and a mixture of plants like grass 

 and alfalfa were the plants tested. Calcium was used in the 

 form of calcium sulphate, calcium carbonate, and tri-calcic phos- 

 phate, while the magnesium was used in the form of the carbo- 

 nate. The calcium and magnesium were all employed in vari- 

 ous combinations with each other and with potash and nitrogen. 

 As a result of these investigations it was found that gypsum de- 

 pressed the yield in the grass and alfalfa mixture. With larger 

 applications the reduction in yield was found to be proportionate 



5»Bul. Col. Agr. Tokyo, Japan, vol. 2, p. 378. Cited from E. S. R., vol. 7, 

 p. 86!), 1895-6. 



*» Paul Parey, Berlin, 1896. Cited from E. S. R., vol. 8, p. 969, 1896-7. 



«» Bol. Scuola. Agr., vol. 3, p. 140. Cited from E. S. R., vol. 9, p. 749, 1897-8. 



«' Landw. Jahrb., vol. 31. p. 619. 



