Rothamsted Symposium on Trace Elements 



70 



The filtrate was always prepared a few days after the soil samples 

 had been taken. 



Figure 12 gives the results obtained in 1946. The low Mn 

 content found in the foliage coincides fairly well with a low con- 

 tent of exchangeable Mn, although the plots 10 kg, pH 5.75, 

 and 15 kg, pH 5.15, form exceptions. The higher amounts in 

 the plants, however, do not coincide with higher content of ex- 

 changeable manganese. 



Mn 



P-piH. 



1000 



1800 



IdOO 



1400 



II200 



tOOO 



m 



CiOO 

 100 



Beaa 

 PotoCo 



OaLs 



60 00 60 



Textfigure 11.— Manganese content o£ 

 foliage of three crops grown on the same plot 

 (1944). 



In Figure 13 the amounts, as far as they have been estimated 

 in soil sampled in 1947, are presented. The lower amounts in 

 soil sampled on May 22 (ranging from 22-54.1 p.p.m.) are 

 markedly higher than those found in 1946 (3.8-55.5). The 

 amounts found in samples taken on July 7, ranging from 31.1- 

 111, exceed the former figures considerably. 



In Figure 14 all amounts of exchangeable manganese deter- 

 mined in samples taken in 1946 and 1947 are given. The varia- 



