REMEDIAL MEASURES 43 



THE DESTRUCTION OF WEEDS BY MEANS OF 

 CHEMICAL SUBSTANCES 



Up to comparatively recent times the methods 

 adopted by the farmer and gardener for the eradication 

 of weeds were largely those which aim at removing or 

 disturbing the latter by mechanical means. The weeds 

 were ploughed under, harrowed out when young and 

 allowed to dry in the sun, pulled up by hand, or cut 

 off with hoes, spuds, scythes, and other similar im- 

 plements, in the manner already described. 



During the last few years, however, attention has 

 been drawn to the possible destruction of weeds on a 

 large scale by the application of various chemical sub- 

 stances, either in solution in the form of a fine spray, 

 or in a powdered state. 



The materials chiefly employed are ammonium sul- 

 phate, common salt, carbolic acid, sodium arsenite, and 

 the sulphates of iron and copper. The two latter com- 

 pounds have proved the most effective for practical 

 farm purposes, the rest being only applicable in ex- 

 ceptional cases. 



i. Ammonium Sulphate is a well-known fertiliser con- 

 taining nitrogen, and extensively used in small amounts 

 up to i or 1 1 cwt. per acre for the manuring of 

 cereals, root crops, and grass land. In larger doses 

 it checks the growth of vegetation for a time, or kills it 

 altogether. When spread in considerable quantities it 

 prevents the germination of seeds, and when mixed with 

 sand or brick dust it is much used to destroy Plantains, 

 Daisies, and other weeds on lawns and small plots of 

 grass. The weeds are checked or killed, and the grass, 

 although at first more or less damaged, is stimulated to 

 such an extent that it soon chokes out the weeds. 



W T hen placed upon the cut ends of Dandelions, 



