Different Artificial Sources of Nitrogen and of Potash. 183 



Plot 16 received rather more potash, and more soda, 

 magnesia, and sulphuric acid, than plot 19 ; and plot 20, 

 with the same amount of nitrogen and potash as plot 19, 

 received no soda, and less sulphuric acid, but the nitric acid 

 and the' potash were applied to the soil in combination. 



Each plot has maintained a fairly mixed herbage. With 

 only a moderate supply of nitrogen, and this in the form of 

 nitrate, and with a liberal supply of potash, leguminous 

 herbage increased on all three, this increase being mainly due 

 to Lathyrus pratensis, but partly, on plots 19 and 20, to 

 Trifolium repens also. On all three plots the bulk of the 

 gramineous herbage is made up of a good many species ; and 

 011 plot 16, which has been the longest under treatment, 

 the mixture is greater that is, there is less predominance 

 of individual species ; Festuca ovina, Agrostis vulgaris, 

 Alopecuras pratensis, Avena flavescens, and Holcus lanatus 

 are somewhat equally represented, whilst Poa trivialis, 

 Dactylis glomerata, and Lolium perenne each show moderate 

 growth. On plots 19 and 20 Festuca ovina is more 

 prominent, and Holcus lanatus is increasing; Agrostis 

 vulgaris, though abundant, is decreasing ; whilst Alopecurus 

 pratensis, Avena flavescens, Avena pubescens, and Poa 

 trivialis are each fairly represented and increasing. There 

 is, on all three plots, a pretty normal character of growth ? 

 fair proportion of stem, and tendency to maturation of the 

 grasses. 



The yields of dry matter, of nitrogen, and of mineral 

 matter indicate greater maturation or ripeness on plot 20 with 

 the nitrate of potash, than on plot 19 with the nitrate of soda 

 and sulphate of potash. 



Analyses of the ash of the first crops for the seven years, 

 and of the second crops for the three years, show that the 

 produce of plot 16, with the fuller mineral manure and 

 longer continuance of the experiment, contained, both per 

 acre and per cent, in its dry substance, more phosphoric acid, 

 considerably more potash, and rather more magnesia, than 



