KESULTS OF EXPERIMENTS AT ftOTHAMSTED, ON 



THE GROWTH OF LEGUMINOUS CROPS, 

 FOR MANY YEARS IN SUCCESSION ON THE SAME LAND. 



INTRODUCTION. 



The subject of my lecture to-day is the conditions, and the 

 results of growth, of Leguminous Crops ; and, as on former occasions, 

 I propose to draw my illustrations largely from the results of field 

 experiments, and other investigations, conducted at Rothamsted. 



In former lectures I have, in a similar way, considered the conditions 

 and the results of growth of Wheat, and of Barley, as representatives 

 of the great gramineous family ; of some varieties of Turnips, repre- 

 senting the Cruciferce-, of some varieties of Beet, representing the 

 Chenopodiacece ; and of Potatoes, of the Solanew. 



It was found that, within certain limits, the requirements, and the 

 results of growth, of different members of one and the same family, 

 showed certain characteristics in common; whilst those of different 

 families showed more or less of distinctive character. Nevertheless, 

 there are some important points of similarity, as well as of contrast, 

 between the requirements of the agricultural representatives of the 

 Graminete, the Cruci/erte, the Chenopodiacecs, and the Solanece. 



It will be seen, however, that the agricultural representatives of the 

 Leguminosce, all of which are included in the sub-order Papilionacece, 

 and some of which are of much importance in our agriculture, show 

 very marked differences, as compared with those of any of the other 

 families I have enumerated. 



It so happens that, both the scientific interest, and the practical 

 value, of these crops, whether as elements in rotation, or as grown in 

 the mixed herbage of grass-land, depend very largely on the amount of 

 nitrogen which they contain, and on the sources of their nitrogen ; and 

 especially on the great differences in these respects, between them, and 

 the representatives of the other families with which they are grown, 

 either in alternation in our rotations, or in association in our meadows 

 and pastures. 



So much is this the case, that it is essential to a proper under- 

 standing and appreciation, of the characteristics of growth of these 

 crops, and for the illustration of their value and importance as 

 depending on those characteristics, to compare and to contrast the 

 conditions and results of their growth, with those of the crops of other 

 families. 



I will first call attention to the difference in the amounts of nitrogen 

 assimilated over a given area by different crops, when each is grown 



