L 427 ] 



XXXII. 



NOTE ON THE OCCUEEENCE OF THE FING-EE AND TOE DISEASE 

 OF TUENIPS IN EELATION TO THE HYDEOGEN ION CON- 

 CENTEATION OF THE SOIL. 



By W. K G. ATKINS, O.B.E., Sc.D. 



[Communicated by Professor H. H. Dixon, Sc.D., F.E.S.] 



[Read November 22, 1921. Published Febrtjauy 2, 1922.] 



It has long been known that the disease occurs in soils poor in calcium salts. 

 Hall (1910) has collated the results obtained by Voelcker and other workers, 

 which show that finger and toe was feund on turnips gi'owing in soil con- 

 taining calcium, expressed as oxide, to the amounts of 0"14, 0-08, 0"13, 0'31, 

 0'39 per cent, in five cases studied, whereas spots, some in the same fields, 

 with 0'89, 0'52, and 0"43 per cent, were free from it. 



The writer is indebted to Mr. T. Sherrard, Maryborough, Douglas, Cork, 

 for the notes on the behaviour of two fields and for soil samples. 



1. " This sample is infested very badly with finger and toe. No turnip 

 or cabbage can grow in this soil." 



2. " This sample is from the same land, only a stream of water dividing 

 the fields. No trace of finger and toe is found here. It is absolutely free 

 from fungus, and grows fine turnips." 



Sieving showed that in each pebbles, &c., which did not pass 30 mesh to 

 the inch, amounted to 23 per cent, of the air-dry soil. Of the good field, 65, 

 and of the bad, 64 per cent, passed the 100-mesh sieve. The soil which passed 

 the latter was found to contain 0'17 and 0'40 per cent, of lime in samples 

 Nos. 1 and 2 respectively. In view of previous work, it is safe to attribute 

 the behaviour of the two fields to their difference in calcium salts. The 

 good field is, however, rather dangerously depleted, as Hall records disease 

 in sandy soil with 0'31 per cent, of calcium oxide, and in clay soil with 0'39. 

 The addition of lime or limestone to the bad field is clearly indicated, 

 and it would probably benefit the other also. 



The acidity of these soils was determined by the colorimetric method, 

 as described and explained in a previous paper (Atkins, 1921). It was 

 observed that the reaction was only very slightly different, the good field 

 being less acid by an amount estimated at pH O'l, using brom thyuLol 

 blue and brom cresol purple as indicators. With neither was there 



