74 



manure in some instances, .particularly on soils rich in 

 organic matter, such as those in the Fens. Even on 

 soils containing less organic matter the beneficial effect 

 is noticeable, and as much as half a ton per acre is 

 sometimes applied. Superphosphate, kainit, and other 

 non-nitrogenous manures are most effective when sown 

 early in the season. 



Nitrate of soda and sulphate of ammonia are highly 

 valuable sources of nitrogen. Their action is very 

 rapid, and. if heavy dressings are applied they should 

 be put on in two applications the first when the crop 

 is appearing above ground, and the second just pre- 

 viously to moulding up. 



The application of large quantities of kainit is said 

 to deteriorate the quality of the tubers, causing them 

 to be watery rather than floury. This, however, should 

 not altogether deter growers from using it, as if the 

 soil is deficient in potash it is absolutely necessary that 

 it should be applied. 



Soot varies very ranch in its manurial properties, as 

 it is liable to adulteration. House soot is almost 

 distinct from factory soot. Soot such as that analysed 

 above is very valuable, and is obtained from house 

 chimneys. Factory soot contains a much greater pro- 

 portion of mineral matter, or valueless dust drawn into 

 the chimneys and flues by powerful blasts. Such soot 

 often contains less than half the nitrogen found in- 

 house soot. Soot is very frequently adulterated, as it- 

 lends itself to adulteration very readily. When soot 

 is bought by weight heavy dust or fine sand is mixed 



