USE OF CHARCOAL AS A MEDIUM FOR PLANT GROWTH. 475 



is brought forward a little later to prove that from time immemorial 

 peat charcoal had been acknowledged to possess valuable fertiHzing 

 qualities, and that inventors and discoverers in those piping times 

 had only discovered " a lost sheep in the wilderness." 



Charcoal does not appear to have progressed in market value 

 during the 'fifties as it would have done had its application been 

 successful. 



In a lecture to the Society of Arts in 1855 Mr. Longmaid said 

 " It is useful to apply by drill or broadcast 4-7 cwts. to the acre to 

 all green crops. It will also be found valuable on clayey soils." 



About 1881 it appears to have been used on wheat land to prevent 

 rust, and it is recommended to gardeners for Auricula soils. 



In 1891 W. Thomson, writing to this Journal on soils and manures 

 for grapes, says : ' ' Charcoal is an excellent addition to soil where clay 

 is in excess." Indeed at this time it was frequently used for making 

 up vine borders. Interest in the use of charcoal has recently been 

 revived in a paper* by M. D. Prianichnikow, of the Agricultural 

 Institute of Petrovskoe (near Moscow). After discussing the theory 

 of Whitney and Cameron in the light of the Rothamsted experiments 

 on continuous wheat-growing, he goes on to describe his own experi- 

 ments with Russian soils (black earth) which are supposed to be infertile 

 on account of the toxins which they contain. He extracted these 

 sick " soils with water and after filtering the extract through charcoal 

 he found that he got a greatly increased growth over that produced 

 in the extract which had not been filtered through charcoal. He 

 grew oats, wheat, buckwheat, maize, and other crops in these soils to 

 which he added charcoal. Better crops were obtained from the 

 soils treated in this way than from the untreated, and he concludes 

 that charcoal renders the supposed toxic excretions inert. 



When he grew the same kind of plant in the same soil year after 

 year he found the crop rapidly diminished. On adding charcoal 

 to the soil, however, the crop was well maintained. 



He ends his paper by saying : " Nous estimons que Taction utile du 

 charbon dans les cultures repetees doit etre etudiee pour qu'on puisse 

 constater definitivement si Taction utile du charbon est en relation 

 avec Texistence des excretions nuisibles des racines, ou si les causes de 

 ce phenomene sont d'un autre ordre." 



If toxins are excreted by the roots of plants it is possible that the 

 charcoal has in some way rendered them inert, but up to the present 

 time it has not been satisfactorily shown that such substances are 

 in fact produced. 



♦ Revue GSnSrale de Botanique, tome 25 bis, 1914. 



3 K i 



