1 920.] 



Notes on Manures. 



37 



The Wheat Bulb Fly and Nitrate of Soda.— There is some 

 evidence that dressings of nitrate of soda are helpful to wheat 

 crops attacked by the Wheat Bulb Fly 

 Notes on Manures (Hylcmyia coarctata) provided that the 

 for May: injury has not gone too far. The nitrate 

 From the Rothamsted helps by enabling the plant to send out 

 Experimental Station, new shoots and thus to keep going until 

 the danger of the attack is passed. 

 Manuring for Potatoes and Root Crops. — Many experiments 

 have shown that a good dressing for potatoes grown in the 

 ordinary way is 10 to 15 tons of dung supplemented by 1 cwt. 

 sulphate of ammonia, 4 cwt. superphosphate, 1 cwt. sulphate 

 or muriate of potash. Where, however, there is reason to 

 anticipate a yield of more than 7 or 8 tons of potatoes per 

 acre the quantities of fertilisers should be considerably increased 

 — the superphosphate up to 7 cwt. per acre, and the potash up 

 to 2 or even 2\ cwt. per acre. Increases in ammonia, however, 

 must be carefully considered ; if the dung is rich and made with 

 cake, probably \\ cwt. sulphate of ammonia is as much as can 

 safely be given. In most cases, however, owing to a shortage 

 of cake the dung is likely to be poorer than usual, in which case 

 sulphate of ammonia can be increased up to 2 \ cwt. per acre. 



In Cheshire steamed bone flour proved better than super- 

 phosphate, and where it can be obtained at about £14 per ton 

 it makes an economical fertiliser for potatoes ; it can be 

 applied at the rate of 5 cwt. per acre. 



The potato crop seems to need phosphates particularly on 

 the Fen soils and in the West, where the rainfall is high and 

 the soils rich in organic matter. In the Eastern Counties, 

 however, on sands and silts containing small quantities of 

 organic matter, it is doubtful whether heavy dressings of 

 phosphates are necessary ; probably no more than 4 cwt. 

 would ever be needed. Where potash can be obtained at 

 anything from 8s. to 10s. per unit it should be used for potatoes 

 this season, owing to the fact that the soils have become some- 

 what depleted of potash during the War. Several potash 

 salts are now available ; the muriate at £22 per ton (50 per 

 cent, of potash) costs 8s. gd. per unit, whereas £24 per ton 

 for sulphate (48 per cent, of potash) corresponds to 10s. per 

 unit. 



Where potash is unobtainable the omission ma}' not be 

 serious in cool, moist districts ; nevertheless, anyone who 

 wishes to make sure of his potato crop will be well advised to 

 use a potassic fertiliser. 



