48 RESULTS WITH WHEAT 



We have already mentioned that the soil at Woburn con- 

 sists of a very fine sand of great depth. Such soils are seldom 

 met with. When favourably situated, and properly treated, 

 they yield a larger return for the manure applied than any other. 

 Hilgard, in America, has already pointed out that a sandy 

 soil is far more fertile in proportion to its contents of plant 

 food than a loam or clay. 



It will be recollected that at Rothamsted the return from 

 400 Ibs. of ammonia salts was as good as the return from 200 

 Ibs., the larger dressing could thus be employed with full 

 profit. At Woburn, where the ammonia salts yield a much 

 better return, this is not the case ; the first 50 Ibs. of ammonia 

 give an average increase of 15 bushels, the second 50 Ibs. add 

 only 7 bushels. This is w r hat would be expected. At 

 W 7 oburn a smaller quantity of ammonia suffices for a crop as 

 large as the soil and season are capable of producing, and 

 large dressings are consequently attended with a diminished 

 rate of profit. It happens, however, that the return from 100 

 Ibs. of ammonia at Woburn is practically as good as that 

 yielded by 50 Ibs., although this does not appear from the 

 figures given in the table. During the last fourteen years 

 plot 8 has been divided, and while both halves have every 

 year received superphosphate and alkalies, the ammonia salts 

 have been applied on the two halves alternately. In this way 

 the residual effect of the previous dressing of 100 Ibs. of 

 ammonia has each year been ascertained. If we add the 

 residual effect during fourteen years to the produce mentioned 

 in the table, we find that the return per cwt. of sulphate of 

 ammonia is 8 bushels in the case of plot 8, as it is in the case 

 of plot 5. On plot 5, the ammonia salts have been continu- 

 ously applied, and their residual effect is therefore included in 

 the average produce mentioned. 



5. Influence of Ammonia salts on the Quality of the 

 produce. The use of ammonia salts for wheat does not unduly 

 increase the proportion of straw to corn unless the quantity of 

 of ammonia used is in excess of that yielding a maximum return 

 of corn. Thus in the Rothamsted results (Table V), we see that 

 in the return per cwt. of sulphate of ammonia the proportion of 



