Manurial Effect of Cut Wheat Straw. 163 



of the respective soils reveal no essential differences, and, 

 independently of the manure, the only known difference 

 between plot 13 and plot 9 is that the former receives earlier 

 afternoon shade. 



On plot 13 the herbage has become even more markedly 

 gramineous than on plot 9. Leguminosse have almost equally 

 disappeared on both ; and the miscellaneous species have 

 greatly decreased on both, Eumex Acetosa being the only 

 prominent weed on either, Conopodium denudatum (Bunium 

 flexuosum, earth-nut or pig-nut, an umbellifer) coming next. 

 The increase on the straw plot was almost entirely com- 

 posed of grass, which, compared with plot 9, contained very 

 much more Dactylis glomerata, this, on plot 13, becoming 

 the most prominent species ; about the same proportion of 

 Agrostis vulgaris, considerably less Holcus lanatus, very 

 much less of Festuca ovina, and especially of Poa pratensis ; 

 but, on the other hand, a fair proportion of Alopecurus 

 pratensis (meadow foxtail), which is scarcely represented on 

 plot 9 ; whilst Avena pubescens, Avena flavescens (yellow 

 oat grass), and Poa trivialis (rough stalked meadow grass) 

 have gone down on both plots. 



If all the nitrogen of the straw became available, it would 

 supply about 91b. per acre per annum, presumably a smaller 

 proportion at first, and more and more each year. Hence 

 there was on plot 13, compared with plot 9, no excess of 

 yield of hay and of nitrogen in the earlier years, but a 

 considerable excess over the latter half of the period ; and 

 there was an increase of about lOlb. of nitrogen per acre 

 per annum over the twenty years. Probably the growing 

 plants were enabled to avail themselves of more also of the 

 other supplies of nitrogen within the soil. 



There was some increase in the amounts taken up of all 

 the mineral constituents, but the most marked was of 

 potash an average of about 231b., of phosphoric acid about 

 41b., and of chlorine about 81b., within each case more over the 

 second period than over the first. There was, too, an average 



M 2 



