18 The Rofhamsted Wheat Experiments. 



III.-EXPERIMENTS ON THE CONTINUOUS 



GROWTH OF WHEAT UPON THE SAME LAND 



FOR FORTY YEARS. 



WHEAT has now been grown for more than forty years in 

 succession on the same land at Eothamsted, and since the 

 eighth year of the experiments each plot has, year after year, 

 received uniform treatment as regards manuring, the varia- 

 tions in this latter respect comprising (1) without manure, 

 (2) with farmyard manure, (3) with a great variety of 

 chemical manures. As an example of an experiment in 

 which the same kind of crop is grown on the same land, 

 subject to uniform manurial treatment, year after year, this 

 elaborate investigation is unique, both in its long continuation 

 and in the maintenance of uniformity of conditions. To the 

 R. A. S. Journal, Messrs. Lawes and Gilbert contributed, in 

 1864, the " Report of experiments on the growth of wheat 

 for twenty years in succession on the same land," and, twenty 

 years later, there appeared the " Report of experiments on 

 the growth of wheat for the second period of twenty years 

 in succession on the same land." These papers occupy 

 altogether about 240 pages, some eighty of which are devoted 

 to figures in the form of appendix tables. It will be conve- 

 nient to discuss the report in its entirety, as that of forty 

 years' continuous experiment. 



In commencing their first report, the authors remark that 

 the records of a field of 14 acres, in which wheat has been 

 grown without manure, and by different descriptions of 

 manure, year after year, for twenty successive seasons, 

 without either fallow or a fallow crop, and in which the 

 lowest produce was in the first year 15, and in the last 17| 



