On the Influence of Solubility on Availability. 



BY 



G. DA1KUHARA. 



Various former experiments carried out in Komaba and Nishigahara 

 have shown that for several Gramineae the best ratio of lime to magnesia 

 lies between i/i and 2/1. With oats the yield was nearly equal in both 

 cases while with upland rice the ratio 1/1 was more favorable than 2/1 and 

 for barley before its flowering period 2/1 was more favorable. With the 

 development of seed, however, relatively more magnesia is required and 

 also in the case of barley the final ratio will be nearer to 1/1 than 2/1. 

 These ratios, however, correspond to equal availability of lime and magnesia, 

 both having been applied as natural carbonates or as nitrates. The ratio of 

 lime to magnesia entering the plant changes, however, very considerably when 

 one of the compounds is insoluble in water while the other is soluble. The 

 latter will then much more readily enter into the plant body than the former. 



My former experiment^ with rice showed that with artificial carbonate 



of lime and with magnesia as cryst. sulphate, the best ratio in sand culture 



CaO as carbonate _ 30 

 MgO as sulphate 1 



I have carried out a similar experiment with barley in sand culture, 



applying the lime in the form very finely powdered lime stone. Each pot 



contained 4.5 Kg of dry sand and received the following general manure 



applied in five fractions : 



NaN0 3 10 Gr. 



K._.«0 4 10 Gr. 



KH;,P0 4 15 Gt. 



While the amount of lime was constant that of magnesia was varied as 



follows : 



1). This Bulletin Vol. I, No. i, p. 23-29. 



420042 



