132 M. M. McCooL 



lime-magnesia ratio for each plant." The growth of the plants is injuri- 

 ously affected when magnesia is present and lime is absent in nutrient 

 solution. According to Konovalov the yield is increased with the increase 

 of the proportion of lime to magnesia. 



Culture experiments with rj^e, corn, and kidney beans are reported by 

 Bernardini and Corso (1908). The nutrient solution contained the ratios 

 of lime to magnesia (magnesia as 1) 3, 2, 1, ^, and ^. Rye gave the best 

 result in the solution in which the relation of lime to magnesia equalled 1, 

 and better results with the higher proportions than with the lower; corn 

 gave the best result with the proportion of lime to magnesia equal to 2, 

 and better with the higher than the lower, showing that an excess of lime 

 does less harm than an excess of magnesia. In the pot experiments a soil 

 of known composition was used and the proportions between lime and 

 magnesia were made the same as in the nutritive solution experiments, and 

 the same results were obtained with rye and corn; with kidney beans the 

 proportion of lime to magnesia equal to 3 gave the best result. 



CaO 



Konovalov (1909) studied the ratio of for barley, millet, oats, and 



maize. He states: ° 



'' In sand cultures with oats and millet the ratios of lime and magnesia 



13.4 6.7 3.3 1.6 0.8 0.4 



varied as follows: ; ■ — , — , — , — — , — , -• 



1 111111 



" The data clearly show that the more lime there is in the nutritive 

 solution the quantity of magnesia remaining the same, until the ratio of 

 lime to magnesia becomes 6.7:1 the greater the yield of both millet and 

 oats. When this ratio is exceeded the yield of millet decreases somewhat 

 and that of oats very considerably, there being a falling off in yield of both 

 grain and straw and the mean weight of the grain." 



In water cultures with maize and barley, 'Hhe maximum yield of organic 

 matter was obtained in case of barley when the ratio of lime to magnesia 

 was 3.3: 1 and in case of maize when the ratio was .8:1. The same ratio 

 gave the maximum yield of above ground material." 



Novel experiments with wheat and oats were conducted by Hansteen 

 (1909). He inserted one of the primary roots of the same seedling into 

 each of tv/o glass tubes placed side by side. The tubes contained separate 

 solutions; for example, in tube 1 was placed N/50 Ca(N03)2, while tube 2 

 contained N/50 Ca(N03)2 + N/50 MgS04. In this manner Hansteen 



