516 



Mr. A. D. HaU 



[May 2i, 



time of Queen Elizabeth down to the beginning of the nineteenth 

 century. This conservative farming about 1840 began to give place 

 to the* third stage in the development — intensive farming, rendered 

 possible by the discovery of artificial fertilizers and the cheap freights 

 which brought foreign fertility in the shape of cheap feeding stuffs 

 to the soil of this country. By these means the average production 

 of the land of the British Isles has been raised from the twenty-bushel 

 level to something over thii'ty bushels, and the most intensive farmers 

 reach an average level at least 25 per cent, higher. In their case the 

 soil has become practically a manufacturing medium transforming the 

 nitrogen and other- fertilizing materials added to it into crops, giving 

 nothing to those crops from its original stock, and indeed up to a 

 certain point gaining rather than losing fertility with each year's 

 cultivation. The inner history of these three stages in agriculture 

 may be followed by a consideration of certain experimental plots at 

 Eothamsted. We may begin with the experimental wheatfield which 



Experiments on Wheat, Broadbalk Field, Rothamsted. 



Average Produce of Grain, first 8 vears (1844-51) and the successive 

 10-year periods 1852-1911. 



is now carrying its sixty-ninth successive crop of wheat. One of the 

 plots has been without manure throughout the whole of that period. 

 The production, which fell steadily for the first ten years, has since 

 that time remained so constant that the slow falling off which we 

 still believe to be taking place is disguised by the fiuctuations due to 

 season. The average yield is about twelve bushels to the acre, almost 

 exactly the average yield of the wheat lands of the whole world. Un- 

 fortunately samples of soil were not taken at the very outset, but if 

 we begin with the earliest analyses that were available in 1865 and 

 draw up a balance-sheet for the nitrogen, we shall find that the removal 

 in tlie cro]i is almost exactly balanced by the small amount that comes 

 down in the rain and the decrease that has raken place in the amount 

 of nitrogen in the soil. There are, however, other losses of nitrogen 

 not brought into account ; some is washed away by drainage water 

 every year, and a further small unestimated amount gets removed as 



