ESSENTIALS OF PLANT 



As the grain ripens, and the proportion of seed to husk 

 increases, a decrease in the percentage of silica in the ash occurs. 



Ratio of the Essential Elements. The ratio of the essential 

 elements affects the development of the plant to some extent. 

 Director Hall 1 of the Rothamsted Station states that where 

 barley is grown on the plots fertilized with potash and nitrogen 

 without phosphoric acid, the grain hardly matures at all, while 

 the phosphoric acid in the absence of nitrogen and potash causes 

 the grain to ripen early. 



Starting with the fact that lime predominates in leaves while 

 magnesia is in excess in seeds, May, under the direction of 

 Loew, 2 grew tobacco in sand culture with excess of lime and 

 with excess of magnesia, producing in the first experiment a 

 large development of leaves, in the second a very small plant. 

 According to other experiments of Loew and his pupils, the 

 ratio of lime to magnesia is of importance. 



For example, Aso 3 grew rice with various ratios of lime to 

 magnesia. The lime and magnesia originally in the soil were 

 estimated by extracting the soil for 24 hours with cold 10 per 

 cent, hydrochloric acid. Such additions of carbonate of lime 

 or carbonate of magnesia were then made to various pots con- 

 taining 7 kilograms of the soil as were necessary to secure the 

 desired ratios of lime to magnesia. In order to ensure an 

 abundance of plant food, each pot also received 15 grams 

 ammonium sulphate, 15 grams sodium phosphate, and 15 grams 

 potassium carbonate. 



The following are the results of this experiment : 



1 Rothamsted Experiments, p. 80. 



2 Bulletin No. I, Bureau Plant Industry, U. S. Dept. Agr. 



3 Bulletin Tokyo Imp. Uni., 1904, p. 97. 



