PREFACE 



hy T. Wallace, C.B.E., M.C., D.Sc, F.R.I.C. 



Agricultural and Horticultural Research Station, Bristol University, 

 Long Ashton, Bristol 



The symposium on trace elements held at the Rothamsted Experi- 

 mental Station in November 1947 was a notable event to those who were 

 privileged to attend, as it brought together, after the isolation of the war 

 years, a nxmiber of workers from countries in western Europe, Great Britain 

 and the U.S.A., who had been engaged with important investigations in 

 this field during the war. It was also appropriate that the Rothamsted 

 Station should have been selected by the International Union as the home 

 of the conference, as this enabled the members to revive old memories and 

 to meet distinguished Rothamsted colleagues, of whom must be specially 

 mentioned Dr. Winifred Brenchley and Dr. Katherine Warington. 



It is with deep sorrow that we record in this volume the death of the 

 Chairman, Professor B. Nemec, whose charm and geniality were enjoyed 

 by all members of the conference. 



Trace element problems have claimed the attention of plant physiolo- 

 gists for many decades and before the war the importance of deficiencies of 

 iron, manganese, copper, zinc and boron, in restricting the production of 

 various crops in many countries, had been recognised both by scientists 

 and farmers. Under wartime conditions of crop production, the impor- 

 tance of trace elements was gready accentuated. This was due to a num- 

 ber of factors: the urgent need for gready increased production which 

 necessitated the large scale production of special crops; intensified methods 

 of cultivation; the extension of cropping to poorer soils; and the shortages 

 of particular fertiliser materials. 



In England, prior to 1939, trace element problems in crops were of 

 little more than academic interest, with the exception of iron deficiency in 

 some horticultural crops, mainly in fruit trees, and boron deficiency in sugar 

 beet, swedes and turnips. 



During the war, however, boron deficiency in sugar beet, mangolds and 

 many brassica crops was widespread and of serious consequence, and man- 

 ganese deficiency was also prevalent in arable crops over many areas of 

 ploughed up grassland and necessitated special control measures. 



Other problems were also noted which have subsequendy been shovni 

 to be due to deficiencies of other trace elements: failures of cereals on Fen 

 soils due to copper deficiency, of fruit trees due to deficiencies of copper 

 and zinc, and of cauliflowers and broccoli due to deficiency of molybdenum. 



The symposium recorded similar experiences in some of the European 

 countries: in particular, the widespread occurrence of deficiencies of cop- 

 per, boron and manganese, and the practical diflBculties of curing these 

 under wartime conditions. 



Other post-war symposia and conferences in the U.S.A. and else- 



