216 CHEMICAL FERTILIZERS 



skilled hand to put in much work upon his land, his balance 

 sheet, if he had ever produced any, would have been an 

 illustration of mere bankruptcy. To grow everything and be 

 self-supporting even on the best land is compatible with only 

 very low average yields, which can only be raised by an 

 external supply of fertilizer. Fertilizers often do less to feed 

 the crop directly than to maintain the fertility of the land. 

 At the present time it is often necessary to raise the fertility 

 of a land above its previous level, and this can only be done 

 by the generous application of fertilizers, some of which may 

 not produce their full return for several years. 



The Cereals. Wheat, in a typical four-course rotation, 

 follows the ploughed up-lee from the previous hay crop, and 

 generally derives as much nitrogen as it requires from the 

 residues which are left in the soil by the clover or other 

 leguminous plants which formed a large part of the herbage 

 which produced the hay. Where there has been " a bad 

 take of clover in the seeds," the amount of nitrogen collected 

 may be quite insufficient for the needs of the wheat plants, 

 and top dressings of sulphate of ammonia are very valuable. 

 In many cases, especially in the northern parts of the country, 

 oats are now substituted for wheat after lee, since grazing 

 may be carried on much later into the winter before the 

 land is broken up, there is less pressure of work in the later 

 autumn and early winter months, and winter frosts have 

 cleaned the land from insect pests and weeds. Where a top 

 dressing is necessary, from \ cwt. to i \ cwt. of sulphate of 

 ammonia is used, preferably spread over two or three 

 dressings. When wheat follows liberally manured mangolds, 

 very little more fertilizer is required. Where wheat or other 

 cereals are grown continuously on the same land, liberal 

 supplies of both phosphates and nitrogen will be needed, and 

 2-3 cwt. of superphosphate or basic slag, with 2-3 cwt. 

 of nitrate of soda or sulphate of ammonia as top dressings 

 should be applied. As wheat will very rarely be grown on 

 light soils, it is not necessary to consider potash fertilizers. 

 Nitrate of lime and nitrate of ammonia may also be used as 

 top dressings for these crops, but calcium cyanamide is not 



