PREVENTION AND ERADICATION OF WEEDS 61 



In German experiments the dressings used for charlock varied 

 from 90 to 135 Ib. per acre, 1 though in one experiment good 

 results were obtained with only 60 Ib. per acre. 2 In some 

 cases the cereal crops were said to turn rather yellow for a 

 few days after application, but they rapidly recovered, and, 

 benefiting by the nitrogen in the manure, gave bigger crops 

 than when no calcium cyanamide was used. Thistles were 

 also very susceptible and were eradicated along with the 

 charlock. On the other hand, in experiments carried on in 

 North Wales, 3 calcium cyanamide, at the rate of 80 and 120 

 Ib. per acre, had no permanent effect on charlock nor on the 

 crop, and all the weeds recovered from the temporary check 

 they received. 



Good results are reported to have been obtained by treat- 

 ing wild radish with I cwt. calcium cyanamide per acre, but 

 it is best to apply a heavier dressing if the weed is very 

 abundant In one case 1 50 Ib. per acre, applied at the end 

 of April, completely destroyed the radish, but the associated 

 oat crop was eight days later in maturing on account of the 

 heavy nitrogenous manuring. The yield of oats, however, 

 was half as much again as that from the control plots that 

 had been left untreated, the net profit from the use of calcium 

 cyanamide being 2 153. per acre. 4 Lime nitrogen is also 

 effective against poppies. 



Kainit Kainit, at the rate of 4 to 8 cwt. per acre, is said 

 to be quite useful in the suppression of charlock, and also in 

 the eradication of many other weeds, frequently being more 

 effective than either calcium cyanamide or iron sulphate. 

 Heavier dressings are also recommended, from 10 to 16 cwt. 

 per acre. The kainit needs to be very finely ground and 

 should be sprinkled on the plants when they are wet with dew 

 or rain, if possible on the morning of a fine day. For autumn 

 sown cereals the best time of application is February or March, 

 for spring sown corn the manure should be spread soon after 

 the seeds have germinated. On very heavy land it may 

 be necessary to apply a dressing of lime to prevent undue 



1 Dtutsch. Landw. Presse. (4th Nov., 1908), Summ. in Jour. Bd. Agric., XV, 

 P- 7?6; (zist Jan., 1914), Summ. in your. Bd. Agric., XXI, p. 64. 



* Mitt, der deutsch. Landw. Gesell. (aoth July, 1907), Summ. in Jour. Bd. 

 Agric., XIV, p. 568. 



* " Charlock Destruction " (1909), Bull. I, Agric. Dtpt., Univ. Co//., N. 

 Wales, Bangor. 



4 Deutsch. Landw. Presse. (24* Aug., 1912), Summ. in Jowr. Bd. Agric., 

 XX, p. 618. 



