20 RESULTS OF EXPERIMENTS AT ROTHAMSTED, 



The second column shows that, owing to the failure of the Clover, 

 sometimes a cereal crop, Wheat or Barley, was sown; but more fre- 

 quently the land was left Fallow. The produce of Wheat, or of Barley, is 

 given between brackets. 



The amounts of produce entered in the column headed Series 1, are, 

 in each case, the means of those on 3 plots, each of which occasionally 

 received a mineral manure containing potash ; and the results given 

 in the column, Series 2, are also the means of 3 plots, each with the 

 mineral, and nitrogenous manures in addition, occasionally applied. 



It is seen that very large crops of Clover were obtained in the 

 first year, 1849 ; less than one-quarter as much in the third year, 1851 ; 

 and in the fourth year about half as much as in the first. There was 

 then no more Clover until the seventh year, when there was very little. 

 More or less was afterwards obtained in the eleventh, seventeenth, 

 twenty-third (on one plot), and lastly (on one plot) in the twenty-seventh 

 year ; but, in no case excepting in the fourth year, was the amount 

 of produce half as much as in the first year. 



Comparing the results without, and with, the nitrogenous manure, 

 it is shown, in the summary at the bottom of the Table, that the 

 average annual total produce, of Clover-hay, or of other crops, was, 

 reckoned over the 29 years, 1827 Ibs. without, and 2093 Ibs. with, the 

 nitrogenous manure; and, reckoned in the same way, the average 

 annual yield of nitrogen was, without nitrogenous manure 32 Ibs., and 

 with it 36-0 Ibs. Eeckoned, however, over the years of crop only, the 

 yield of nitrogen in the Clover and other crops, was, 7 7 '5 Ibs. per acre 

 per annum without, and 80-2 Ibs. with, the nitrogenous manuring. Or, 

 reckoning the nitrogen in the Clover alone, and only over the years 

 when it gave any crop, the average annual yield of it over those 7 years 

 was, without nitrogenous manure 100*1 Ibs., and with it, 109*3 Ibs. 

 There was, therefore, comparatively little increase, either in the produce, 

 or in the yield of nitrogen, by the use of nitrogenous manures. 



To conclude in regard to these experiments :- The attempt to grow 

 Clover year after year on ordinary arable land, by means of such 

 mineral manures as increase the luxuriance of growth when there is a 

 fair plant, or even by the addition to these of nitrogenous manures, 

 has entirely failed. In view of this failure to grow the crop con- 

 tinuously on ordinary arable land, the next results to which I have to 

 call attention are of much interest and significance. 



GROWTH OF RED CLOVER, YEAR AFTER YEAR, ON RICH GARDEN SOIL. 



In 1854, after it seemed clear that the plant would not continue to 

 grow on the arable land. Clover was sown in a garden, only a few 

 hundred yards distant from the experimental field, on soil which had 

 been under ordinary kitchen-garden cultivation for probably two or 

 three centuries. It is remarkable that, under these conditions, the 

 crop has grown luxuriantly almost every year since ; this year, 1889, 

 being the 36th season of the continuous growth. Further particulars 



