Effect of Manganese Compounds 87 



from the untreated plot, the / Q of water and of total nitrogen being 

 somewhat lower than that from the untreated, while the ash and the 

 quantity of manganese present was the same in the grain from both 

 plots. Bertrand suggested that these results might indicate a new line 

 to follow in the study of the causes of the soil fertility. 



Strampelli (1907) tested the effect of manganese dioxide, carbonate, 

 and sulphate, and of a manganiferous mineral from the Argentine upon 

 wheat, and found that while all four substances exercised a favourable 

 influence on the vegetation, the best result was obtained with the 

 sulphate. When however other manures were used in conjunction 

 with the manganese compounds the balance of improvement shifted. 

 With nitrogen, applied as nitrate of soda, manganese dioxide proved 

 the most beneficial, with farmyard manure the manganiferous mineral 1 , 

 and with blood the carbonate. It was also found that a manganese 

 compost did not increase production when phosphatic manure was 

 applied as basic slag. 



Feilitzen (1907) indicated that the nature of the soil plays its 

 part in determining whether manganese acts as a stimulant or not. 

 His experiments were made in the field on poor moor soil, which 

 carried a little Sphagnum turf and Eriophorum, and which was poor 

 in food salts. The soil was prepared and manured and then the plots 

 were watered with a solution of 1 gm. MnSO 4 . 4H 2 O per litre at the 

 rate of 10 kgm. sulphate per hectare, six control plots being left un- 

 treated. Oats were sown and the soil rolled. During growth no 

 difference was noted between the various plots, and after harvesting 

 the weights of the different crops showed that the manganese had 

 not caused increase of crop in either grain or straw on this poor 

 moor soil. 



The great bulk of the work on this problem has been carried out 

 by various Japanese investigators, whose work extends over several 

 years. Loew and Sawa (1902) found that small quantities of man- 

 ganese sulphate in soil cultures stimulated the growth of rice, pea, and 

 cabbage. They suggested that soils of great natural fertility contain 

 manganese in an easily absorbed condition, and that this forms one of 

 the characteristics of such soils. 



Nagaoka (1903) dealt with plots in the rice fields which had not 

 been manured for the three previous years and which were then treated 

 with manure at the rate of 100 kgm. ammonium sulphate, 100 kgm. 



1 As no analysis of the mineral is given it is obviously impossible to say to what con- 

 stituent the increase is due in this case. 



