CLOVEE GEOWN IN GAEDEN SOIL 145 



III. THE CONTINUOUS GROWTH OF CLOVER ON RICH 

 GARDEN SOIL. 



In 1854, after it seemed clear that clover would not continue 

 to grow on the arable land, it 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. In view of the failures in 

 the attempt to grow clover continuously on ordinary arable 

 land, it is remarkable that, under these conditions, the crop 

 has grown luxuriantly almost every year since 1917 being the 

 sixty-fourth season of the continuous growth. At the com- 

 mencement the percentage of nitrogen in the surface-soil of the 

 garden was four or five times as high as in that of the arable 

 soil of the field ; and it would doubtless be richer in all other 

 manurial constituents also. Indeed, after the growth of clover 

 for twenty-five years in succession, even the second 9 inches of 

 the garden clover soil was found to be still very much richer 

 in nitrogen than the first 9 inches in the Hoos field. Table 

 LV. gives the results for each of the sixty years of experiment 

 with clover on the rich garden soil. The second column 

 shows the number of' cuttings each year, the third the 

 amounts of produce per acre reckoned in the condition of 

 dryness as hay, the fourth the amount of dry substance, 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 two periods of twenty-five years each, over the period of 

 fifty years 1854-1903, and over ten years 1904-13. It should be 

 stated that as the garden clover plot is only a few yards square, 

 calculations of produce per acre can only give approximations 

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

 relied upon so far as their general indications are concerned. 



Confining our attention to the amounts of produce reckoned 

 as hay, and to the estimated amounts of nitrogen in the produce, 

 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 in the first twenty-five years than in the 



K 



