THE LIME-MAGNESIA RATIO 89 



by some of the same investigators whose work has just been re- 

 viewed. Loew,^ together with Aso, pubhshed a paper on the 

 different degrees of availabihty of plant nutrients in which the 

 statement is made that Loew's hypothesis of the Hme-mag- 

 nesia ratio is predicated on an equal availability of the two bases 

 and that the ratio changes wdth the availability of the bases, be- 

 cause more of the base will enter the plant when the compound 

 is more available. Thus the ratio of the bases which is offered 

 to the roots is different from that which is found in the plant. 

 In these investigations it was also found that magnesia in the 

 "burnt" form was more available than in the form of pul- 

 verized magnesite, and that magnesium sulphate is still more 

 available than the first. The authors arrange for an "agronom- 

 ical equivalent" which represents the amount of easily avail- 

 able forms of lime and magnesia which are equivalent to 100 

 parts of the natural calcium and magnesium carbonates in the 

 form of the finest powder. They explain that calcium carbonate 

 acts differently from gypsum in the soil because the latter has a 

 low degree of availability since dilute acids do not make it more 

 soluble. Therefore, the claim is made that even large applica- 

 tions of gypsum do not essentially alter the Hme content of the 

 leaves, and an excess of gypsum is not so injurious therefore, as 

 an excess of calcium carbonate. Finally, the claim is made that 

 decrease in harvest which follows the liming of some soils, is due 

 rather to the production of a bad ratio between lime and mag- 

 nesia than to decreasing the available phosphoric acid supply. 



Daikuhara,^" again, in a study of barley, found that the yield 

 of that crop is doubled on well manured soil by making the ratio 

 of lime to magnesia 1 to 1 through the addition of more lime, 

 since the natural soil wdth which he worked contained lime to 

 magnesia as 0.34 to 1. The yield was even more than doubled 

 when the fertilization was one-sided, or when no apphcation of 

 fertilizers at all was made. The actual percentages of' lime and 



. » Bui. Col. Agr. Tokyo, Japan, vol. 6, p. 335. Cited from E. S. R., vol. 17, 

 p. 121, 1905-06. 



10 Bui. Imp. Cent. Agr. Ex. Sta. Japan, vol. 1, p. 13. Cited from E. S. R., 

 vol. 17, p. 1149, 1905-06. 



