ACTION OF MANGANESE IN SOILS. 7 



of the investigators, however, have given detailed description of the 

 composition and character of the soil. A good deal of evidence has 

 been secured by Kelly 1 and others which tends to show that the 

 effect, whether beneficial or harmful, is an indirect one. The results 

 show in a general way that manganese is beneficial to certain trees 

 and leguminous crops and is harmful to root crops. It also seems 

 that manganese is not stimulating to growth when applied to an 

 acid soil. 



EXPERIMENTS WITH MANGANESE SALTS IN POTS. 



The effect of manganese salts was tested on soils in paraffined wire 

 pots according to the method described in Circular 18 of the Bureau 

 of Soils. Wheat was the plant used as the test crop. The soil was 

 weighed out in pans and treated with the various manganese salts 

 in different amounts and allowed to stand in a moist condition for a 

 week before planting. Five pots were used for each treatment and 

 six wheat plants grown in each pot. The wheat was grown in the 

 greenhouse for a month and then was cut and the weight of the 

 green plant taken. Five pots of untreated soil were included in the 

 experiment as a check. The increase or decrease in weight of the 

 treated plants over the untreated was taken as the effect of the 

 manganese. 



The soil used in this experiment was a sandy loam, which was 

 unproductive in the field, and did not respond well to general fert 

 zers. Five manganese salts were worked with, each in five different 

 concentrations, namely 10, 25, 50, 100, and 250 parts per million 

 of Mn. The salts tested were the chloride, sulphate, nitrate, carbo- 

 nate, and dioxide of manganese. The salts , ^ dissolved or sus- 

 pended in water and applied to the soil. It w *a thoroughly mixed 

 by sifting and after one week was put in the pots and planted to 

 wheat. The wheat came up uniformly and grew well. Tai>le 1 

 gives the relative growth due to the various treatments. The 

 growth in the untreated soil is taken as 100 and the figures, there- 

 fore, represent relative green weight. The plants grew from Sep- 

 tember 30 to November 6. 



Table 1. — Effect of manganese on growth of wheat plants in an unproductive sandy loam 

 soil. Untreated taken as 100. 



Manganese 













(parts per 



MnCl 2 . 



MnSO<. 



Mn (NO g ) 2 . 



MnC0 3 . 



Mn0 2 . 



million). 

















100 



100 



100 



100 



100 



10 



119 



122 



116 



111 



108 



25 



129 



121 



121 



119 



104 



50 



131 



101 



101 



100 



110 



100 



115 



122 



100 



91 



111 



250 



103 



116 



103 



89 



104 



i Loc. cit. 



