824 EXPEEIMENT STATION RECORD. 



BOTANY. 



Recent investigations concerning the effect of perchlorates on 

 the grovrth of crops, V. de Caluwe {O/yaa/i Yer. Oudlc< r. liijks. 

 Laiidhoua'schooJ, 12 {1900), M. 11(3, j^P- 105-109, figs. .?).— During- 

 recent years it has been noted that grain fields, especially rye, are 

 more or less seriously injured when fertilized with nitrate of soda 

 containing perchlorates. The plants thus poisoned remain stunted; 

 the leaves are short, stiff, and twisted, and the color is a very dark 

 green. It has been a matter of dispute whether the injury was due to 

 perchlorate of soda or of potash, though the evidence points to the 

 former as the principal cause of the disease. The experiments carried 

 on b\^ the author in 1898 and 1899 demonstrated that sodium per- 

 chlorate is more injurious than potassium perchlorate. 



For all of the experiments except one a field of rye that had 

 been sown in the fall of 1898 was selected. This was cut up into plats 

 and treated with sodium nitrate and with varying amounts of per- 

 chlorates of soda and of potash. There were (1) plats on which no 

 fertilizer was used; (2) those to which only sodium nitrate was 

 applied, and (3) those that received sodium perchlorate or potas- 

 sium perchlorate without sodium nitrate. In the first series of experi- 

 ments mixtures of 1, 2, and ?> per cent of the perchlorate and chlorate 

 of potash with sodium nitrate were used. Check plats in each series 

 received the equivalent of 2 per cent chlorate and perchlorate, but no 

 nitrate of soda. The fertilizer was applied Februarj^ 23, 1899, and in 

 April the s3'mptoms of perchlorate poisoning were clearl}^ evident. 

 The plats treated with chlorate did not show the symptoms of per- 

 chlorate poisoning, but the leaves were pale and etiolated in spots. 

 The plats receiving chlorates and perchlorates, but no nitrate, showed 

 very few symptoms of either the perchlorate or chlorate poisoning, 

 although the growth was weak, owing to the absence of nitrates. The 

 plats treated with sodium nitrate alone gave an inci^ease of 31 to 33 

 per cent over the untreated plats, those to which chlorates as Avell 

 as nitrate had been applied gave an increase of only -1 to 7 per 

 cent, while on the 2 plats treated with perchlorates and nitrate there 

 was a decrease in yield. The possible good effect of the nitrate was 

 counteracted by chlorate and perchlorate, and the injurious effect of 

 the latter was shown to be greater than that of the former. 



The tests to determine the effects of sodium perchlorate were carried 

 on at the same time and in a similar manner, except that twice as many 

 plats were used and the percentages of perchlorates for the different 

 plats varied from 0.75 to 2.6 per cent. Two plats were given per- 

 chlorate without nitrate. The injurious effects of the perchlorates 

 were evident before the end of March. As compared with the plats 

 treated with nitrate of soda alone the plats that received sodium per- 



