128 M. M. McCooL 



tilized in one case w'ith material obtained from a place near Belvidere, 

 New Jersey, and in another case with material obtained from Oxford, 

 New Jersey, showed injurious effects in the former, and beneficial action in 

 the latter, on the crop growth. The difference between the two reactions 

 was so striking that it was considered of importance to investigate the 

 cause. Samples of the two limestones were sent to the United States 

 Department of Agriculture, where they were analyzed. The injurious lime- 

 stones w^ere fomid to contain thirty-eight to forty-two per cent of magnesium 

 carbonate, while the beneficial Imiestones contained not Cjuite one per cent 

 of this substance. 



Adolf ]\Iayer (1886) mentions unproductiveness as characteristic of soils 

 rich in magnesia. On the other hand, Heiden (1869) cites some instances 

 in which magnesia, and even magnesium sulfate, were beneficial when used 

 as fertilizers on soil. 



There are conflicting reports regarding the value of kainit and carnallite 

 as fertilizers under different conditions. Kainit is composed of K2SO4, 

 MgS04, MgCl2, and water of crystallization. Carnallite is a double 

 chlorid of potassium and magnesium. The eft"ects were frequently found 

 to be injurious when the salts v/ere applied in spring, while the application 

 in autumn proved beneficial. Thus Fleischer (1886) observed that when 

 kainit was applied in autumn the yield of a crop of potatoes was five per 

 cent greater than when kainit was applied in spring. Liebenberg (1896) 

 reported a decrease in the yield of meadows when kainit was applied in 

 autumn. In the latter case the perennial roots of grasses came in direct 

 contact with the fresh fertilizer; while in the previous cases winter rains 

 washed out or modified the injurious magnesium salt before seeds were 

 so^ai. 



The detrimental action of these salts is due mainly to their high mag- 

 nesia content • — which will do little harm on soils rich in lime and poor 

 in magnesia. The more magnesia there is present in a soil, in relation 

 to lime — other conditions being constant — the more injurious a certain 

 additional quantity of magnesium compounds will prove. 



It is thus evident, from these general experiments, that there are contra- 

 dictory reports on the results from the application of various amounts of 

 lime and magnesia to the soil. If it be assumed, however, as is permissible 

 from data subsequently mentioned, that there is a certain favorable ratio 

 between lime and magnesia, and particularly an injurious action from an 



