ON THE GROWTH OF LEGUMINOUS CROPS. 27 



manured plot, which had yielded so much more nitrogen in the crops, 

 only 0-2236 per cent., or nearly one-tenth less. 



Calculated per acre, the surface-soil of the mineral manured plot, to 

 the depth of nine inches, contained, at the end of the twenty years, 506 

 Ibs. less nitrogen than that of the unmanured plot to the same depth ; 

 corresponding to an annual reduction of 25 '3 Ibs. per acre per annum. 



Without pretending to claim absolute accuracy for such results, and 

 such calculations, it is, to say the least, a very remarkable coincidence, 

 that whilst the estimated increased yield of nitrogen per acre per 

 annum, in the mineral manured crop was 23 '6 Ibs., the estimated 

 increased loss of nitrogen by the surface soil should be 25 *3 Ibs. per 

 acre per annum. 



In reference to the fact that, according to the results, the resources 

 of the surface soil would seem to have been mainly, if not wholly, 

 drawn upon, it should be observed, that the potash of artificial manures 

 is almost exclusively retained in the superficial layers of the soil, and 

 that the leguminous plant that was the most prominently developed 

 was the Lathyrus pratensis, which, although it has also deep roots, 

 throws .out an enormous quantity of feeding root near the surface ; 

 whilst the prominent plants of other families were also those 

 characterised by superficial rooting. 



Here, again, then, in these results with the mixed herbage of grass 

 land, as in those with the Clover on the rich garden-soil, there seems to 

 be clear indication that the soil is an important source of nitrogen to 

 Leguminosse. 



The next illustrations will bring to view the curious result that, on 

 soil where one leguminous plant has practically failed, another plant of 

 the same family may grow luxuriantly, and in some way obtain very 

 large amounts of nitrogen. 



RED CLOVER GROWN AFTER BEANS. 



The experiments to which I have now to direct attention, were 

 made in the field which had been devoted to experiments on the 

 growth of beans for a period of 32 years; but which, as has been seen, 

 so far failed that an average crop was seldom obtained ; whilst the 

 amount of nitrogen taken up over a given area, though still much more 

 than in ^o^-Leguminous crops grown under similar conditions, was, 

 after the first few years, much below the amount in a fairly average 

 Bean-crop. After the cessation of the experiment with Beans in 1878, 

 the land was left fallow for between four and five years, to 1882 

 inclusive, when Grass-seeds were sown, but failed. On this land, on 

 which the attempt to grow the Leguminous-crop Beans had been 

 abandoned, Barley and Clover were sown in the spring of 1883. 



Before considering the results of this new experiment, it will be 

 well briefly to call attention to the direct experimental evidence as to 

 the condition of the soils. Thus, in April, 1883, before the Barley 

 and Clover were sown, the surface-soil (free of stones, and reckoned 



