THE DISTRIBUTION OF FERTILIZERS 205 



of the year. The trampling of sheep consolidates the soil, 

 which is usually light and stony, and provides much manure 

 for the subsequent turnip crop. Thus much of the farmyard 

 manure used for the turnip crop in other parts of the country 

 is supplied on the spot by the sheep. 



A modification of the Norfolk four-course rotation, which 

 is often known as the East Lothian rotation, consists of seeds, 

 barley, hay, oats, potatoes or beans, and in the sixth year 

 wheat. It will be noticed that the cereals are varied, although 

 frequent, and that either a cleaning crop or nitrogen collecting 

 crop, like beans, is introduced previous to the wheat. Here, 

 again, the general principles are that most of the farmyard 

 manure goes on to the turnips, the barley getting little, the 

 seeds getting heavy dressings of superphosphate, and the 

 potatoes and beans being well manured with artificials as 

 well. Such a system has the great advantage of distributing 

 the labour well over the different parts of the rotation. 

 Further possible improvements in the existing systems of 

 rotation in the British Isles seem chiefly to lie in some exten- 

 sion of the system of catch cropping. Catch crops, however, 

 require an extensive rainfall, which is more likely to be 

 obtained on the western side of the British Isles than on the 

 east. Catch cropping requires extensive fertilizing, and 

 needs considerable quantities of sulphate of ammonia and 

 superphosphate to produce its best results. Further improve- 

 ments of existing rotations will mainly lie in the direction 

 of a larger production of leguminous crops, so that nitrogen 

 may be added to the soil after it has been collected by these 

 crops from the air. Further improvements will also probably 

 consist in the development of strains and varieties of seed 

 which will be more capable of resisting insect enemies and 

 fungoid disease. 



For allotment and garden crops it is found beneficial to 

 practise some system of change, so that the same kind of 

 crop does not occupy the same piece of ground on two 

 successive years. Owing to the small area and the large 

 variety of crops, it is almost impossible to practise any 

 definite system of rotation. In many gardens, especially 



