16 



Yield of Nitrogen in Melilotus Lencantha. 



One more striking illustration of high yield of nitrogen by a 

 plant of the leguminous family, this time on soil which had not 

 received any nitrogenous manure for nearly thirty years, must be 

 given. In 1878, the land upon which attempts had been made to 

 grow red clover in frequent succession since 1849, was devoted to 

 experiments with fourteen different descriptions of leguminous plants ; 

 so that the present season, 1882, is the fifth year of the experiments. 

 The object was to ascertain whether, among a selection of plants, all of 

 the leguminous family, but of different habits of growth, and especially 

 of different character and range of roots, some could be grown success- 

 fully for a longer time, and would yield more produce, containing 

 more nitrogen as well as other constituents, than others; all being 

 supplied with the same descriptions and quantities of manuring sub- 

 stances, applied to the surface soil. Further, whether the success in 

 some cases and the failure in others, would afford additional evidence 

 as to the source of the nitrogen of the Leguminosas generally, and as 

 to the causes of the failure of red clover in particular, when it is 

 grown too frequently on the same land. Fourteen different descrip- 

 tions of plants were jelected, and, after two or three immaterial 

 changes, the list at the present time includes eight species or varieties 

 of Trifoliurn, two of Medicago, Melilotus leucantha, Lotus corniculattis, 

 Vicia sativa, and Onohrychis sativa. 



Of the numei'ous species or varieties of Trifoliwn, all gave but 

 meagre produce, excepting T. incarnatum. The Lotus corniculatus 

 also gave very small produce. The two species of Medicago, the black 

 Medick, and the purple MedicJc or Lucerne, and the OnohrycJiis, or 

 common Sainfoin, gave much more ; the Vicia sativa or common 

 vetch, more still. But of all, the Melilotus leucantha, or Bokhara 

 clover, has yielded the most. It is estimated that, taking the average 

 of four years, 1878-81, it yielded about 70 pounds of nitrogen per 

 acre per annum, on plots which have received no nitrogenous manure 

 for more than thirty years; whilst the produce of the fifth season, 

 1882, is heavier than in either of the preceding years ; and it is esti- 

 mated to contain about 150 pounds of nitrogen. In fact, in the 

 second, as well as in the fifth year, the melilotus yielded considerably 

 more than 100 pounds of nitrogen per acre ; and on the average of 

 the five years it has yielded between 80 and 90 pounds per acre on 

 this nitrogen-exhausted soil. 



How long this very luxuriant growth,- and this very high yield of 

 nitrogen per acre, will continue, is a question of very great interest. 



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