FIELD CROPS. 893 



Yield of iarley with peat poudrette and nitrate of soda. 



Fertilizer. 



No nitrogenons fertilizer. . 

 Peat poudrette, sprinfr 1803 

 Peat poudrette, fall 18SI2. . . 

 Nitrate of soda 



Yield per hectare. 



Grain. 



2, 4:«. 

 3, 139. 

 2, 627. 

 3, 429. 



Straw 

 and chaff. 



Kg. 

 6, 176. 5 

 8, 037. 

 6, 742. 5 

 8, 768. 5 



Phosphatic slag for potatoes. — The effect of 3 kinds of pliosphatic slag 

 on potatoes was investigated during 1803. "Finshytte" slag is made 

 from ferruginous Gellivara apatite and is named after the place of manu- 

 facture. Martin's slag is obtained by treatment of Gellivara iron ore 

 in the Martin process. These 2 slags contained 10.94 per cent and 

 17.83 per cent of phosphoric acid, respectively, while the Thomas slag 

 applied contained 18.54 per cent of this ingredient. The plats were 

 fertilized in the fall of 1892 at the rate of 100 kg. of potash per acre, in 

 tlie form of sulphate, and 120 kg. of phosphoric acid in the different 

 phosphatic slags ; 2 plats received only potassium sulphate. 



The average results for the duplicate plats were as follows: 



The starch content and yield of potatoes. 



Fertilizer per hectare. 



100 kg. sulphate of potash 



100 kg. sulphate of potasli 



120 kg. phosphoric acid in Thomas slag. 



100 kg. sulphate of potash 



120 kg. phosphoric acid in Martin's slag 



100 kg. sulphate of potash 



120 kg. phosphoric acid in Finshytte sla 



Starch 

 content. 



Per cent. 

 13. r 



12.8 

 12.5 

 11,9 



Yield per hectare.. 



Tubers. Starch 



Kg. 

 10, 941 



13, 815 



14, 648 

 11, 471 



Kg. 

 1, 433. 27 



1, 768. 32 

 1, 831. 00 

 1, 365. 04 



Lem Strom's frost torches (E, S. R., 5, pp. 660-662) were used with 

 marked success in the preceding experiments for preventing frost on 

 the potatoes during several nights in the month of August. In the 

 opinion of the author the Lemstrom peat frost torches are the most 

 convenient, effective, and inexpensive combustive material for the 

 generation of smoke as a preventive of damage from frost. The 

 expense of torches is exceedingly small compared with the value of 

 the crops in danger. Less than 100 torches are required per acre of 

 land, the cost of which in the European market is given as 64 cts. — 



F. W. "WOLL. 



Rotation of crops, J. B. Lawes and J. H. Gilbert {Jour. Roy. 

 A(jr. Soc. England, 3d ser.j 5 (1894), No. 30, pp. 585-646).— This is a 

 comprehensive discussion of the results of rotation experiments at 

 Eothamsted, England, begun in 1848. The four-course rotation con- 

 sisted of (1) Swedish turnips (rutabagas), (2) barley, (3) clover (or 

 17034— No. 10 4 



