Section Y 
HOOS FIELD LEGUMINOUS AND WHEAT-FALLOW SOILS. 
INVESTIGATIONS SHOWING THE EFFECT OF VARIOUS LEGU- 
MINOUS CROPS ON THE NITROGEN CONTENTS OF THE SOIL. 
When referring to the linos field barley SOilfi I drew your attention 
to a striking effect produced on the SOU of a certain plat OH whieh 
barley had been continuously gTOWO tor a very Long period with full 
mineral fertilizers but without nitrogen. The nitrogen in the soil of 
this plat was found t<> l><- very appreciably greater than in the easeof 
plats Liberally treated with nitrogenous fertilizers, and the difference 
was shown to be due to tin* eomparat i ve encouragement given by the 
mineral fertilizers, in tin' absence of nitrogen supply, to a certain 
leguminous weed (Jfedicago luptUina) which is noticed to be extraor- 
dinarily prevalent among the bailey on this plat. 
In the same field there has been carried out over many years a most 
interest ing set of experiments on Leguminous crops, and also a contin- 
uous experiment on the growth of wheat on iinmanured land, both 
year after year and in alternate years with intervening Fallows. The 
examination of the soils from the various Leguminous plats and from 
the wheat land has yielded results of great comparative interest. 
The leguminous experiments were brought before you by Sir Henry 
Gilbert in L8W, and I should be apologetic for again discussing them 
but for the fact that the object of my own lectures would be conspic- 
uously unfulfilled if they did not include the interesting analyses 
made from time to time of these particular soils from I loos field; and 
I would add that the leguminous experiments have been, since Sir 
Henry Gilbert addressed you, followed by the growth of wheat on the 
same plats, with results to which we shall have to allude later. Abbre- 
viating Sir Henry's account of the leguminous experiments, it nmy be 
stated that their object was to ascertain whether certain leguminous 
crops of different habits of growth, especially as to root range, could 
be successfully grown for a longer time and with a larger annual pro- 
duce than others, all being similarly treated as regards fertilizers; 
and also to ascertain w hether the successor failure of individual spe- 
cies would afford new evidence as to the source of the nitrogen of the 
Leguminosse generally, and as to the causes of what is familiarly 
know n as "clover sickness." The experiments were started in 1878, 
on land on w hich red clover had been grown, though with precarious 
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