31 



PART II 

 AGRICULTURAL RESULTS 



OBTAINED BY THE APPLICATION OF 



SULPHATE OF AMMONIA TO CROPS 



Our object in this section is to show what are the results 

 to be expected from the application of ammoniacal manures to 

 the chief crops grown by the British farmer. For this purpose 

 we shall endeavour to bring together the various records 

 which have been published of accurate trials in the field. As, 

 however, the produce yielded by manures is extremely 

 different in bad and good seasons, we shall generally avoid 

 quoting any experiments relating to a single season, but shall 

 rely chiefly on experiments showing the average produce of the 

 same manure over many years. Average results are seldom 

 of a startling character, but they are the only ones which we 

 can safely reckon on to be maintained in actual practice. 



Besides the weight of produce yielded by the use of a unit 

 weight of sulphate of ammonia, we shall endeavour to 

 indicate in each case what has been the influence of the 

 manure on the quality and composition of the crop. 



WHEAT 



i. Experiments at Rothamsted. The results obtained 

 at Rothamsted, Herts, will be most appropriately men- 

 tioned first. The Rothamsted field experiments were the 

 earliest exact trials of the effects produced by modern artificial 

 manures, and they have been also the longest continued. 



The soil at Rothamsted is a heavy loam with many flints, 

 the subsoil usually contains more clay ; it lies on the chalk, 

 which, however, is many feet below the surface. The chalk 

 provides a good natural drainage. The soil contains very 

 little lime, except at the surface, where it is well provided 

 with this substance, having received in ancient times, accord- 

 ing to the custom of the country, many dressings of chalk. 



The plan of the field experiments at Rothamsted has been 

 to grow the same crop year after year on the same land with 



