406 The Eradication of Wild Onion. 



successful in largely reducing, if not in actually getting 

 altogether rid of the pest. 



The applications tirst tried were those which had been in 

 use at the Pot-culture Station, others being added, and fresh 

 plots taken as the work developed. As " farmers' applications," 

 lime and gas lime were employed ; of " chemical " applications 

 carbolic acid, sulphuric acid, sulphocyanide of ammonium, 

 arsenic, sulphate of copper, common salt, sulphate of magnesia, 

 chloride of magnesium, carbolised lime, and various other 

 materials were tried ; thirdly, of " mechanical " nature were 

 the following : cutting off the flowering heads, pulling up the 

 plants by hand, deep-ploughing of the land, lightening the soil 

 by road-drift, burning the soil, raising the top 8 inches of 

 soil and putting three inches depth of ashes below it. This 

 work occupied from February, 1902, to the close of 1904. As 

 the practical outcome, none of the " farmers' " nor of the 

 "chemical" applications really effected any permanent improve- 

 ment. Gas lime (used locally as a remedy), carbolic acid, and 

 sulphocyanide of ammonium all seemed to exercise some 

 benefit, but salt made the weed more vigorous ; the other 

 " remedies " were all unsuccessful. In many cases the new 

 growth from seed or " bulbil " was killed, but nothing seemed 

 to touch the hard " off -sets " thrown off from the bulb. Cutting 

 off the flower-heads only made the stem and bulb more vigorous 

 and gave rise to more " off -sets " : even hand-pulling did not 

 do good, and though quantities of plants were removed and 

 bui-nt, there seemed to be a more abundant crop than ever next 

 season ; burning the soil was, of course, too expensive ; deep- 

 ploughing also seemed only to bring more bulbs to the surface. 

 In short, the only methods which, in the field, seemed to promise 

 any real success were the application of road-drift and the 

 lightening of the land by an under-bed of ashes. While the 

 use of road-drift certainly did good, it was not nearly as good 

 as the employment of ashes. The latter was, of course, only 

 tried on a small scale, and would be impracticable on a large 

 one. But its success pointed to the conclusion that it was in 

 the direction of finding some means by which the soil could be 

 rendered lighter and less retentive of water, that success might 

 be achieved. This had been ascertained already at the Pot- 

 culture Station, for, when soil in which wild onion grew had 

 water entirely withheld from it, the onions died ; further, it is 

 known that wild onion does not mature in light, well-drained 

 soil. Accordingly, future work was pursued in this direction, 

 and " chemical " treatment was confined to the use of carbolic 

 acid and sulphocyanide of ammonium. 



In the autumn of 1904 all the old plots were ploughed up 

 and the whole area divided into five strips, each ^jj acre in 



