42 THE MANURING OF ARABLE LAND [CH. 



Suitable dressings are: 



4 to 6 cwts superphosphate or basic slag, 1 to 2 cwts 



nitrate of soda or sulphate of ammonia. 

 For any of the above crops seaweed should be used to supple- 

 ment the dung if it can possibly be obtained. 



CEREALS. 



Wheat. 



Wheat is generally grown (a) after potatoes or roots drawn off, 

 (6) after seeds grazed, or dressed with dung. It is often followed 

 by barley, but in present circumstances farmers ought to see 

 whether it cannot be taken a second time in place of part of the 

 barley. The necessary conditions for two successive crops are 

 given later. 



Wheat is perhaps next to grass the least difficult crop a farmer 

 can grow at the present time for it can usually do very well without 

 dung or potash manures. For this reason dung should not be 

 used unless the requirements of the potatoes and root crops have 

 been fully satisfied. The rule breaks down, however, in dry 

 districts ; in parts of Norfolk, for instance, dung is almost indis- 

 pensable for the wheat crop. 



The two fertilisers to which wheat responds most are nitrogen 

 compounds and phosphates. 



Nitrogen compounds. Farmyard manure has usually been 

 applied to the crop preceding wheat and sufficient material re- 

 mains in the soil for a grain crop. But under war conditions 

 it is desirable to increase the stocks of available nitrogen and this 

 can most conveniently be done by top dressings of nitrate of soda 

 or sulphate of ammonia in spring. Such dressings are particularly 

 necessary : 



(a) When the winter rainfall has been heavy and has washed 

 out the reserves of nitrate from the soil. 



(6) When the crop is standing still in spring and falling a 

 victim to an attack of some pest such as wireworm. 



In either case a little nitrate of soda will help the crop along. 

 The great advantage of nitrate of soda is that it begins to act at 



