24 



TABLE XI. 



Too much reliance must not be placed on these figures, as 

 the last two periods are comparatively short, and the returns 

 may be affected by variation of the seasons. The dif- 

 ferences, however, -bet ween the produce of the two systems 

 of manuring the purely mineral and the mineral and nitro- 

 genous probably fairly represent the comparative efficacy of 

 the three methods of applying the ammonia salts. 



We may take it, therefore, that the system of putting on a 

 small dressing of sulphate of ammonia in the autumn, but 

 reserving most of it until the spring, is the most economical 

 for such a crop as wheat. The spring dressing should 

 usually be given some time in March or early in April, so 

 that the later spring rains may serve to distribute it through 

 the soil. 



In the case of spring-sown crops, there is no question that 

 sulphate of ammonia should be applied in spring only, for 

 there is no object in patting on any of it in autumn. 



STAGE OF GROWTH BEST FOR THE APPLICATION OF 

 SULPHATE. 



With regard to the period of growth of the crop at which 

 sulphate of ammonia may best be applied, everything points 

 to the advisability of using it so as to supply nitrogen to the 

 earliest stages of the plant's growth, as well as later. Apart 

 from autumn-sown crops, therefore, we find that the applica- 

 tion of sulphate of ammonia at the time of sowing the seed 

 gives the best results. There is then a short time allowed 

 for nitrification before the plant requires a supply of nitro- 

 genous manure. In early spring, when nitrification is slow, 

 it may even be sown and harrowed in a few days before the 

 crop is sown. It has been suggested that better results 

 would follow if sulphate of ammonia were ploughed in at the 

 last ploughing for the crop ; and in a very dry season, this 

 might be advantageous, as the manure would be better 

 mixed with the soil. In an average spring, however, in 

 this country, there is usually enough rain to distribute the 

 sulphate of ammonia through the soil ; and it must be 

 remembered that when it had been ploughed in, it would be 

 subject to great loss from nitrification and subsequent 

 drainage, if wet weather came on and delayed sowing. 



