PREVENTION AND ERADICATION OF WEEDS 49 



heavy harrow run over the stubble will drag up much of the 

 weed, and if the latter be collected into heaps and burnt there 

 and then on the ground, the ashes help to fertilise the soil and 

 the land is more fit for ploughing. This may be done even on 

 heavy land when " running grasses " are a nuisance. On light, 

 sandy land this is the recognised method of dealing with 

 twitch, as at every available opportunity the cultivator is run 

 over the soil to gather the stuff up ready for burning. 



It is occasionally possible to take advantage of the pre- 

 ference of weeds for certain soils in order to eradicate them 

 or to prevent them from being spread from place to place. 

 Sheep's sorrel (Rumex acetoselld] requires soil of a very open 

 and light nature, and anything that consolidates the soil tends 

 to suppress the weed. Anderson (I/79) 1 quotes an instance 

 of an experiment in which sheep's sorrel was eradicated by 

 thoroughly rolling the land. Many weed seeds are carried 

 about in farmyard manure, and as the weeds that are most 

 abundant on heavy land differ from those that prefer light soil, 

 Hardie (1904) 2 suggested th'at wherever possible the manure 

 made from straw grown on heavy land should be put on to 

 light land, and vice versa, and then the weed seeds would 

 have less encouragement to flourish in their new environment. 



The methods above described are those that are applicable 

 to arable land irrespective of the crops carried. The crop 

 itself, however, can be used as a valuable instrument in weed 

 eradication, whether on account of its habit or the particular 

 type of cultivation it requires. Roots are most valuable 

 cleaning crops, and are often sown when a piece of land has 

 grown so foul that it needs special treatment. Most root 

 crops, as mangels, swedes, and turnips, are sown so late in the 

 season that a long time is available in the spring for cultivat- 

 ing and clearing the land of weeds as described above. Then, 

 when once the crop is up, it needs constant attention and 

 cultivating from first to last. The horse-hoe is used to clear 

 the spaces between the rows, later on hand-hoeing takes place 

 to single the plants, and to the very end it is necessary to 

 keep the land well worked if a good crop is to be obtained. 

 All this cultivation and working of the soil is the very thing 

 to clear the weeds out of the way. The weed seeds find a 

 perfect seed bed in which they germinate, only to be cut down 



1 Anderson, J. (1779), " Essays on Agriculture," Vol. II, pp. 215-226. 

 a Hardie, W. (1904), "Destruction of Weeds by Surface Cultivation," 

 jfour. Bd. Agric., XI, pp. 193-201. 



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