Rothamsted Symposium on Trace Elements xiv 



Conclusion 18 



References 18 



Discussion 18 



Deficiencies of Minor Elements Caused by Excesses hy 



Leo Gisiger, Dr.sc.techn. (Eidg. Agrikulturchemische 

 Anstalt, Liebefeld-Bern, Switzerland) 19 



The Problem 19 



The Influence of Liming on Boron Deficiency ... 19 

 The Fixation Hypothesis in Partial Contradiction to 



Experiments 19 



The Nature of the Injurious Effect of Overliming 



Acid Soils 21 



Can the Damaging Excess, Caused by Overliming, Be 



Removed!' 22 



The Antagonism between Boron and Hydroxidb COH)- 



loNs 25 



The Causes of Grey Speck Diseases 26 



Opinions and Results 26 



QtncKLiME AS Well as Boron May Favour or Prevent 



THE Occurrence of Grey Speck Disease .... 26 

 The K:Ca Relation and Its Influence on Grey Speck 



Disease 27 



Summary 29 



References 29 



Discussion 30 



Criteria of Essentiality of Inorganic Micronutrients for 



Plants with Special Reference to Molybdenum hy D. L 



Arnon, Ph.D. (Division of Plant Nutrition, University of 



California, Berkeley, California) 31 



Agricultural Evidence of the Essentiality of Micro- 

 nutrients 31 



Biochemical Evidence 32 



Determination of the Essentiality of Micronutrients 34 

 Experiments on Tomato waTH Different Groups of 



Micronutrients 35 



References 38 



Discussion 39 



A Memorandum Regarding Nomenclature hy D. I. Arnon, 

 Ph.D. (Division of Plant Nutrition, University of Cali- 

 fornia, Berkeley, California) 40 



Importance of Copper and Molybdenum in the Nutrition 

 of Higher Plants and Micro-Organisms hy E. G. Mul- 

 der, Ph.D. (Landbouwproefstation, Eemskanaal, Gronin- 

 gen, Netherlands) 41 



