306 Messrs, j. b. lawes and j. h. gilbert on the results of 
distribution of the roots of the collective mixed herbage growing under the influence 
of the nitrate, giving it a command of the stores of a correspondingly increased range 
of soil and subsoil. Again, it is well known that (in whatever combination it does so 
in either case) the nitrogen of nitrate of soda distributes much more rapidly, not only 
in the upper but also in the lower layers of the soil, than does that of the ammonia- 
salts. Direct observation has further shown that, with this, there is a greater develop¬ 
ment of some of the deeper rooting species, and consequently a greater distribution of 
roots in the lower layers. Thus, the mixed herbage growing under the influence of 
the nitrate draws more upon the deeper layers; it has, therefore, a greater supply of 
mineral constituents at its disposal; and hence, though taking more from the soil 
itself, it shows exhaustion much more tardily. How much the action of the nitrate of 
soda, or of its products of decomposition, in liberating or rendering available otherwise 
locked up constituents of the soil and subsoil, may have contributed to the result is 
obviously a question worthy of consideration. 
The results of plot 17 show the effects of nitrate of soda applied in quantity 
supplying only half as much nitrogen as that of the ammonia-salts of plot 5, or of the 
nitrate of soda of plot 15. 
The figures show much more produce and increase over the first, second, and total 
periods, by the use of nitrate of soda in this smaller quantity, than by that of ammonia- 
salts containing twice as much nitrogen; indeed, there was, over the first period only 
201 lbs., over the second only 158 lbs., and over the total period only 176 lbs., less hay 
per acre per annum, than was obtained by double the amount of nitrate of soda. Further, 
the yield is only 2 per cent, less over the second period compared with the first. 
Of nitrogen in the produce, the smaller quantity of nitrate of soda gave somewhat 
less over the first period, but considerably more over the second, and more over the 
total period, than twice the quantity applied as ammonia-salts ; and there was, at the 
same time, comparatively little decline in yield over the second period compared with 
the first. There was, however, an average of about 8 lbs. per acre per annum less 
nitrogen in the produce by the smaller than in that by the double amount of nitrate 
of soda; but there was, nevertheless, a much larger proportion of that supplied 
recovered in the increase of crop where the smaller quantity was used. 
It has been seen how strikingly greater was the amount of mineral matter taken up 
under the influence of a quantity of nitrate containing the same amount of nitrogen 
as the ammonia salts ; and it is even more remarkable that here, with only half the 
quantity of nitrate, there is, over the whole period, within about 1 lb. per acre per annum 
as much mineral matter removed in the crop as with the double quantity, whilst the 
falling off in amount over the second period is even rather less. There was, indeed, 
even more lime, more potass, and more silica, taken from the soil in the crops grown by 
the smaller than in those by the larger amount of nitrate, and at the same time 
nearly as much magnesia and phosphoric acid. The deficiency was mainly due to 
much less soda being taken up. 
