42 RESULTS WITH W H EAT 



are able to mention were made at Rothamsted and at 

 Holkham, it will be most convenient to consider the question 

 in this place. 



It is easy to see that under certain circumstances the 

 application of ammonia salts in the spring may have decided 

 advantages, while under other circumstances an application in 

 the autumn would be preferred. If the application of ammonia 

 salts in the autumn is followed by excessive rain, the nitrates 

 formed in the soil may be washed through, and lost as 

 drainage water before the wheat plant commences to grow in the 

 spring. On the other hand, if a top-dressing of ammonia salts 

 in spring is followed by a continuance of dry weather, the 

 manure remains for a long time ineffective. If we could fore- 

 tell the occurrence of either kind of season we should know 

 which time of application to prefer. Opinion is now generally 

 in favour of the spring application of ammonia, but it must be 

 admitted that excellent results have often followed an autumn 

 application. 



At Rothamsted autumn dressing was for a long time 

 employed ; it was usual for the ammonia salts to be spread 

 broadcast, and ploughed or harrowed in before drilling the 

 wheat. The largest return ever obtained from ammonia salts, 

 namely the increase of 20 bushels from 200 Ibs., and of 34 

 bushels from 400 Ibs., was obtained in 1863 from autumn 

 dressings. For the crop of 1873, and afterwards, a comparison 

 of the effect of autumn and spring applications has been 

 regularly made at Rothamsted. The application in spring has 

 been as a simple top-dressing, left to be washed in by rain, 

 and not followed by the use of a harrow. From 1878 to 1883 

 the ammonia salts were applied in the spring, usually in 

 March, on all the plots save one. From 1884 to the present 

 time, each plot, save one, has received 100 Ibs. of ammonia 

 salts in the autumn, the rest of the ammonia salts being 

 applied in the spring. The following table shows the com- 

 parative effects produced at Rothamsted by the autumn and 

 spring application of 400 Ibs. of ammonia salts during eleven 

 years, 1872-1883. The land always received superphosphate 

 and alkalies, which were applied in the autumn. 



