OCTOBER 175 



ous growth. For, be it noted, it is only on sound, 

 well-drained land that bracken will flourish. Examine 

 any moorland or unreclaimed hillside, and you will not 

 see a frond on the sour or boggy parts. Nor is it only 

 in the northern counties that this pest has established 

 itself and is rapidly spreading. Driving not long ago 

 from Dorchester to Abbotsbury we passed over Black 

 Down, a wide expanse of what ought to be sound chalk 

 pasture. Hundreds of acres of that breezy upland are 

 covered with a dense growth of bracken shoulder high, 

 showing that the land is of such quality as might bear 

 good crops or be afforested with advantage. 



Persistent cutting, year after year, when the fronds 

 are three-parts grown, has been proved effectual in 

 extirpating the fern ; but the cost of doing so over wide 

 extent is almost prohibitive, and no direct return can 

 be expected ; whereas, if a valuable fertiliser can be 

 secured by burning the fern after it is cut, the land 

 may be rid of a pernicious weed without net loss. 



In order to ascertain the true value of bracken as a 

 source of potash, I sent a supply in July 1917 to 

 Professor Henry Greenish, Director of the Pharmacy 

 Research Laboratory in Bloomsbury Square, who kindly 

 undertook its analysis. He reported as follows : 



' I find that the fern when dried in a warm room and 

 completely burnt to a nearly white ash, yields 4'82 per cent, 

 of ash. The ash contains 41 -82 percent, of potash, K 2 O. 

 The dried fern itself would therefore yield 2 per cent, of 

 potash, or 50 tons of the [dried] fern would yield about 2 '41 

 tons of ash, in which there would be about 1 ton of potash. 

 If the fern is not quite completely burnt the quantity of ash 

 obtained is higher, and the proportion of potash in it is lower. 



