254 



THE ROTHAMSTED EXPERIMENTS. 



Relation of 

 rotation to 

 economical 

 manuring. 



Rotation 

 and sale of 

 produce. 



Rotation 

 and distri- 

 bution of 

 labour. 



Rotation 

 and clean- 

 ing land. 



gathering and assimilating the various mineral constituents, 

 and the nitrogen, of the different crops, are concerned. It 

 cannot be doubted that the difference in the amounts, in the 

 conditions of combination, and in the distribution within the 

 soil, of the various mineral constituents, is at least an element 

 in the explanation of the benefits of alternation ; nor, on the 

 other hand, can there be any doubt that the facts relating to 

 the amount, and to the sources, of the nitrogen of the different 

 crops, are of still greater significance than are those in regard 

 to the mineral constituents. 



But, it is not only the conditions of growth, but the uses of 

 the different crops when grown, that have to be taken into 

 account. Thus, the cereals, when grown in rotation, yield 

 more produce for sale in the season of growth than when 

 grown continuously. Again, the crops alternated with them 

 accumulate very much more of mineral constituents and of 

 nitrogen in their produce, than do the cereals themselves ; 

 and, by far the greater proportion of those constituents re- 

 mains in circulation in the manure of the farm, whilst the 

 remainder yields highly valuable products for sale in the 

 forms of meat and milk. 



Further, independently of the benefits arising from the 

 difference in the requirements and results of growth of the 

 different crops, of the increased amount of manure available, 

 and of the increased sale of highly valuable animal products, 

 there are other elements of advantage of considerable import- 

 ance. For example, with a variety of crops, the mechanical 

 operations of the farm, involving horse and hand labour, are 

 better distributed over the year, and are therefore more 

 economically performed. Last, but by no means least, the 

 opportunities which alternate cropping affords for the clean- 

 ing of the land from weeds is a prominent element of ad- 

 vantage. 



Thus, then, the benefits of rotation are very various; and 

 the explanation of them, though largely dependent on the 

 facts which have been ascertained by scientific investigation, 

 also largely involves considerations connected with the 

 general economy of the farm ; and since, as has been seen, 

 so large a proportion of the produce grown is retained on the 

 farm, as stock-food or litter, it is obvious that the benefits 

 cannot be fully appreciated without arriving at some definite 

 idea of the importance to the farmer of the saleable animal 

 products, and of the manure obtained. This subject will 

 be considered in Section VI., which now follows. 



