To what Extent should a Soil be Limed? 



BY 



T. Furuta. 



The application of lime in agriculture can aim at two effects: 

 [. to improve the physical and chemical condition of the soil; 2. 

 to provide the plants with a sufficient amount of lime which is 

 for them an indispensable nutrient. It is the latter point alone 

 which comes under discussion in this paper. Of course, liming 

 will always be in order when a soil is exceedingly poor in lime, 

 but this is not the only condition which necessitates liming for 

 the nutrition of the plants. It is also in order in all cases where 

 the soils contain an excess of magnesia over lime. 1 But to what 

 extent will liming be necessary in such a case ? The amount 

 of lime to be incorporated with a soil to any given depth is a 

 very important item since an excessive liming will depress the 

 yield. The first requirement for a calculation is of course an 

 analysis of the soil. 



An ordinary soil analysis however will only show the 

 amounts of lime and magnesia as a whole, but will not convey a 

 proper idea of the extent to which these bases are easily avail- 

 able for the plants, since the roots can merely attack the surface 

 of large particles of hydrous silicates, carbonates and phosphates, 

 while very small particles can be wholly dissolved and absorbed 

 by them. In order therefore to determine the extent of liming 

 necessary for the next crop, 2 only the assimilable amounts of 

 lime and magnesia need to be determined and these amounts, 

 alone ought to be taken as a foundation. 



Some consider iooo kilo, of carbonate of lime per hectare a 



1 Cf. O. Loew : On the physiological n'>le of mineral nutrients, U. S. Dep't of 

 Agriculture, Washington 1899. 



2 Sometimes even in limestone regions fields may be benefitted by liming. This is 

 the case when the carbonate of lime has been washed out from the surface of the fields, 

 or when the limestones contain also magnesia (dolomitic limestone). 



