1920.] 



877 



ments carried out in sand or water cultures, but there is a very 

 marked difference between these conditions and those obtaining 

 in the soil. There is little, if any, evidence that small quan- 

 tities are effective, and only occasionally are results obtained 

 indicating that larger amounts are beneficial. 



Use of Potash on Grass Land. — The question has been asked 

 whether potash fertilisers are as beneficial as slag on grass land. 

 Potash fertilisers do not produce so striking a change as slag; 

 nevertheless, they are often of value on land laid in for hay, 

 increasing both the quality and the quantity of the herbage. 

 It is not so clear, however, that they are effective on grazing 

 land, although even here improvement has resulted, especially 

 on light or chalky soils. As a rule potash might be expected 

 to give good results on any grass land where salt is known to be 

 beneficial. In such cases the muriate would probably be as 

 effective as the sulphate. 



Sylvinite as a Potassic Fertiliser. — A correspondent who uses 

 large amounts of potash states that he is experiencing some 

 difficulty in securing suppHes, and asks whether sylvinite is 

 likely to be useful. This material is supplied in two grades, 

 the declared analyses of which are : — 



Description of the Salts. 



Potassium 

 Chloride. 



Sodium ! Calcium 

 Chloride, j Sulphate. 



Insoluble. 



Sylvinite 14% (French Kainite 

 12—14% K.,0) ... 

 do. 20—22% K.3O 



Fer cent. 



19—25 

 32-35 



i 



Fer cent. ; Fer cent. 



60—66 2—5 

 50 — 55 2 — 5 



Fer cent. 



10—12 

 9—10 



There is every reason to beheve that this material is of consider- 

 able value to mangolds, and on light and chalky soils for wheat 

 and temporary leys. It might not prove so useful as sulphate 

 of potash for potatoes, however, owing to the large amount of 

 chlorides present. 



Effect of Magnesium Salts as Fertiliser. — A correspondent 

 has asked whether the magnesium salts "present in kainit are 

 likely to be harmful, or whether they might not exert some 

 beneficial effect. 



For ordinary farm crops, and particularly mangolds, sulphate 

 of magnesia is not harmful, and indeed it may exert a beneficial 

 effect. This is shown in the Eothamsted experiments on wheat. 

 The crop yields were as follows : — 



