10 The Rothamsted Experiments. 



the two plots, it being, however, rather in favour of the 

 autumn-sown manure. In straw there is a difference of only 

 81b. per acre in favour of the spring-sown manure. Upon 

 the whole, then, the results are in favour of sowing these 

 soluble manures in the autumn, even in so light a soil. On 

 the autumn-sown plot there was a fall in the produce of 18 

 bushels, and on the spring-sown plot of 14J bushels per acre, 

 from the first year to the average of the last three years. 



Plot 5 received the same manure as plot 2, and as plot 

 3 or 4. The result was to produce over the four years from 

 53 to 54 bushels of corn more than was yielded by the 

 minerals alone, besides a larger quantity of straw. This, 

 therefore, was an annual average of 13 to 14 bushels of corn, 

 and an equivalent of straw, due to the use of the ammonia 

 salts. And since there was in the four years about twenty 

 bushels more increase by the mixture of both minerals and 

 ammonia-salts than by the latter alone, it is obvious that 

 the minerals of this last 20 bushels of the total 53 of increase 

 were derived from the mineral manures employed. 



On plot 7, 14 tons per acre of farmyard manure were 

 annually applied, and gave an average annual increase of 

 about 10 \ bushels of corn and 13001b. of straw less by nearly 

 3 bushels of corn and about 1501b. of straw than the produce 

 obtained by the rape-cake (plot 6). As the other plots demon- 

 strated, in their results, that neither minerals alone, nor car- 

 bonaceous organic matter (in the rape cake), had any influence 

 in the increase of the crop, but that wherever there was a, 

 supply of nitrogen in the manure there was always a very con- 

 siderable increase, it is concluded that it was the amount of 

 nitrogen liberated from the dung, in a form assimilable by 

 the plants, which determined the limit to the increase of 

 produce obtained by its use. Though the amount of nitrogen 

 contained in the increased produce of wheat was never equal 

 to that supplied in the manure, it is to be remembered that, 

 besides any liability to loss by drainage, to which all manurial 

 ingredients might be subject, the nitrogen, in several of its- 



