22 RESULTS OF EXPERIMENTS AT ROTHAMSTED, 



The first column after the dates, shows the number of cuttings each 

 year, the second the amounts of produce per acre, reckoned in the 

 condition of dryness as hay, the third the amount of dry substance, the 

 fourth that of the mineral matter, and the last the estimated amounts 

 of nitrogen per acre in the crops. At the bottom of the Table are 

 given the average annual results over periods of 10, 10, 10, 5, and 35 years. 

 I shall confine attention to the amounts of produce reckoned as hay, 

 and to the estimated amounts of nitrogen in the produce. 



It should be stated that, as the garden-clover plot is only a few 

 yards square, calculations of produce per acre can only give approxima- 

 tions to the truth ; but it is believed that they can be thoroughly relied 

 upon so far as their general indications are concerned. It may be 

 added that five times during the whole period, gypsum has been applied 

 to one-third, and a mineral manure containing potash, but no nitrogen, 

 to another third of this plot. 



Casting the eye down the column of produce as hay, it is seen at a 

 glance that, excepting a few occasional years of very high produce 

 during the later periods, the amount of crop is very much greater 

 during the first, than during either of the subsequent periods of 10 or 

 5 years. In fact, as is seen at the foot of the Table, there was an 

 average annual produce equal to 10,689 Ibs. of hay, over the first period 

 of 10 years, but of only 5,561 Ibs. over the second, and 5,099 Ibs. over 

 the third, and of only 4,866 Ibs. over the last 5 years. 



Now, even these latter amounts corrrespond to what would be 

 considered fair, though not large crops, when Clover is grown in an 

 ordinary course of rotation, once only in 4, or in 8 years, or more ; so 

 that the produce in the earlier years on this rich garden-soil, was very 

 unusually large. Indeed, the average annual produce over the whole 

 period of 35 years, nam'ely 6,795 Ibs. more than 3 tons of hay- 

 would be a very good yield for the crop grown only occasionally in the 

 ordinary course of agriculture. 



But it is when we look at the figures in the last column of the 

 Table, which show the estimated amounts of nitrogen in the crops, 

 that the importance and significance of these results obtained on rich 

 garden-soil, are fully recognised ; and this is especially the case when 

 they are compared with those obtained on ordinary arable land. 



Thus, whilst the amount of nitrogen in average crops of Wheat, 

 Barley, or Oats, will be from 40 to 50 Ibs. per acre, of Beans about 100 

 Ibs., of Meadow Hay about 50 Ibs., and Clover Hay grown occasionally 

 in rotation little more than 100 Ibs. ; here, on this rich garden- 

 soil, the produce of Clover has, in one year contained more than 400 

 Ibs. of nitrogen, in three years more than 300 Ibs., in several more 

 than 200 Ibs., and in only eleven years of the 35 less than 100 Ibs. 



In fact, as the figures at the bottom of the Table show, the estimated 

 average annual yield of nitrogen in the above-ground growth was 

 over the first 10 years 256 Ibs., over the second 10 years 133 Ibs., over 

 the third 10 years 122 Ibs., over the last 5 years 117 Ibs., and over the 

 whole period of 35 years 163 Ibs. ; whilst, as the details show, the 



