1042 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



remunerative crop, on the whole, was that obtained when the dressing of 

 nitrate of soda was 2 cwt. per acre. 



In most of the years potash has shown very marked and valuable 

 results on some, if not all, of the plots on which it has been used, even in 

 the presence of dung ; but the effect in 1900 — when, owing to climatic 

 conditions, the crop grew more freely — was less apparent, and, as a result, 

 the average results for the five seasons do not fully indicate the advantage 

 which may sometimes be derived from the use of potash manures for this 

 crop. 



That Tripoli Onions, like Summer Onions, are strongly dependent upon 

 a full supply of potash in some form or other has been shown very 

 strikingly on the undunged plots, especially in 1900. In that season, by 

 the aid of a dressing of 6 cwt. of superphosphate, 1 cwt. of sulphate of 

 potash, and the somewhat heroic quantity of 8 cwt. of nitrate of soda per 

 acre, we raised over lOJtons of Tripoli Onions per acre without any dung 

 at all, on land which had not been dunged for years ; and the whole of 

 the Onions so grown were sound or marketable bulbs. 



On the other half of the plot, however, which received no potash and 

 which, it may be added, has received no potash in any form during the 

 period of our experiments, the plants failed to produce any bulbs at all 

 worth gathering or weighing. 



We may at once say, however, that our experience indicates that it 

 is very unwise to grow Onions without dung, however liberal the supply 

 of chemical fertilisers. 



Returning to the various dunged plots, the comparative effect of heavy 

 dung and of chemical fertilisers used in conjunction with the lighter 

 dressing of dung may be seen in the following table, in which, from the 

 average yield of each plot, a deduction has been made of the weight of 

 Onions produced by the 25 loads of dung alone. 



TRIPOLI ONIONS. 



Annual manuring (in addition to 25 loads Dung) 

 per acre 



Average annual increase per acre 

 over five seasons 



Increase in 

 total weight 

 of bulbs 



Increase in 

 weight of 

 sound mar- 

 ketable bulbs 



Annual cost 



of extra 

 manure per 

 acre 



Phosphates, Potash Salts, and 2 cwt. Nitrate of 

 Phosphates, Potash Salts, and 4 cwt. Nitrate of 



tons cwt. 



3 17 



4 2 

 4 17 



tons cwt. 



2 14 



3 11 



3 5 



£ s. d. 

 5 0 0 



2 5 0 



3 5 0 



The relative economy of the different systems of manuring as here set 

 out speaks for itself. 



Leeks. 



We have grown leeks for four years on a plan of experiment differing 

 from the scheme applied in most of our trials, inasmuch as it includes a 

 plot treated with chemical fertilisers without the use of nitrate. This 

 plan was adopted on account of our experience with Leeks in earlier 



