62 WEEDS OF FARM LAND 



consolidation 1 of the soil. Cereal crops are very little harmed 

 by the kainit and any damage is merely temporary, but peas, 

 beans and other leguminous crops are more liable to suffer, as 

 is usually the case when chemical weed killers are used. A 

 comparison of the various tests made with kainit shows that 

 it varies in its effect upon weeds, so that the latter may be 

 classified according to their degree of susceptibility to the 

 dressing. 



(1) Weeds most Susceptible to Kainit. Charlock, wild 

 radish, black bindweed, speedwell, chickweed, nettle, groundsel, 

 cornflower, mayweed (Anthemis arvensis). 



(2) Weeds Moderately Susceptible. Persecaria, spurry. 



(3) Weeds only Slightly Susceptible. Sowthistle, fumitory, 

 poppy, spreading orache. 



Various Manurial Dressings. Attempts have been made 

 to reduce weeds by attacking before germination the seeds lying 

 in the soil. Any substance that is active enough to destroy 

 weed seeds would be equally harmful to crop seeds, especially 

 cereals, so if this method is adopted it must be tried at times 

 when no crop seeds are lying in the soil, and when a sufficient 

 period will elapse before sowing to permit the corrosive effect 

 of the dressing to pass off. Cornflower seeds in the soil have 

 been successfully destroyed by applications of carbolineum or 

 chloride of lime, and numerous other weed seeds disappeared 

 at the same time. 2 



Spurry is chiefly associated with light soils that are de- 

 ficient in lime, and sheep's sorrel, though it is found on both 

 light and heavy soil, also indicates lime deficiency. Liming 

 has been tried to eradicate both these weeds, with indifferent 

 success in the case of spurry, with rather more success with 

 sheep's sorrel. As a matter of fact the shortage of lime is 

 usually very marked when these weeds are abundant, and it 

 would be necessary to apply an almost impossible dressing of 

 lime so to alter the balance as to render the situation untenable 

 for these weeds. A mere I or 2 tons of ground lime per acre 

 has no effect on spurry, though doubtless it effects some de- 

 gree of improvement in the soil itself. At Hodsock, an ap- 

 plication of 10 cwt. salt per acre on very light sand in poor 

 condition killed spurry in patches, but later on the weed took 

 a fresh lease of life, and grew even more luxuriantly than on 



1 Landw. Jahrb. (1914), Bd. XLVI, pp. 627-657, Summ. in Jour. Bd. Agric., 



P- 451. 



2 Arb. Deutsch. Landw. Gesell. ; see Jour. Ed. Agric. (1914), XX, pp. 909-910. 



XXI, p. 451. 

 rb. 



