95 Steenbjerg: Microelements from a Practical Point of View 



References 



Bendixen, H. C. and Pedersen, J. G. A., 1946: Continued investiga- 

 tions into cobalt deficiency disease acobaltosis in cattle CStmimary) (Year- 

 book of The Royal Veterinary and Agricultural College, Copenhagen, 80). 



Dion, H. G., Mann, P. J. G. and Heintze, S. G., 1947: The "easily 

 reducible" manganese of soils (Journal of Agricultural Science 37:17). 



Heintze, S. G., 1946: Manganese deficiency in peas and other crops in 

 relation to the availability of sod manganese (Journal of Agricultural Sci- 

 ence 36:227). 



Heintze, S. G. and Mann, P. J. G., 1947: Soluble complexes of man- 

 ganic manganese (Journal of Agricultural Science 37:23). 



Leeper, G. W., 1947: The forms and reactions of manganese in the 

 soil (Soil Science 63:23). 



Steenbjerg, F., 1933-5: Investigations concerning the manganese con- 

 tent in Danish soils, I, II, & III (Summary) (Tidsskrift for Planteavl 

 39:401; 40:337; 40:797). 



Steenbjerg, F., 1940: Copper in soils and cultivated plants, with 

 special reference to white-tip disease (Summary) (Tidsskrift for Planteavl 

 45:259). 



Steenbjerg, F., 1943: Copper in soils and cultivated plants, II. In- 

 vestigations on the fertilizing value of copper minerals (Summary) (Tids- 

 skrift for Planteavl 47:557). 



Steenbjerg, P., 1950: On the relative contents of plant nutrients in 

 crops (Trans. Foiuth Internat. Cong. Soil Sci. 1:254). 



Points from Discussion of Pafer hy Prof. Steenbjerg 



Prof. Wallace:— 



1) Has Prof. Steenbjerg any data for soluble copper in 

 instances of varying levels of copper deficiency similar to those 

 for total copper shown in his curves? 



2) In our experience at Long Ashton with total iron content 

 we should not expect a curve similiar to Prof. Steenbj erg's curve 

 for copper. In fact, when iron deficiency is induced by a heavy 

 metal like zinc we have found large accumulations of iron in the 

 iron deficient plants. 



3) In our experience grass has increased the availability of 

 iron to fruit trees but not of manganese and the availability of the 

 latter seems to have been decreased for crops following immedi- 

 ately on the ploughing in of grass swards. This last point seems 



