THEY AFFECT THE GROWTH OF THE STEM. 335 



though the disappoiriifnents which have ocasionally attended their use 

 naturally cause the practical iarmer to hesitate stifl, before he applies 

 them in any quantity to his land. As these salts, especially the nitrate 

 of soda, are comparatively abundant in nature, — as they are really be- 

 neficial in many cases, and can be employed with a profit, — as their use 

 in practical agriculture has recently excited considerable interest — and 

 as many eKperiments fiave in consequence been made with them upon 

 various cropsT — I shall briefly direct your attention to the most impor- 

 tant facts which have yet been established in regard to their action upon 

 the growing plant. 



a. Apparent effects of the Nitrates. — The first visible effect of the ni- 

 trates upon every crop is to impart a dark green colour to the leaves and 

 stems. 2^. They then hasten, increase, and not unfrequently prolong 

 the growth of the plant. 3°. They generally cause an increase both in 

 the weight of hay or straw, and of corn — though the colour and growth 

 are occasionally affected without any sensible increase of the crop. 4°. 

 The hay or grass produced is always more greedily eaten by the cattle 

 than that which has not been dressed, even when the quantity is not 

 affected ; — but the grain is usually of inferior quality, bringing a some- 

 what less price in the market, and yielding a smaller produce of flour. 



Its principal action seems to be expended in promoting the growth— 

 that is, increasing the production of woody fibre, either in the stem or the 

 ear, without so much affecting, except indirectly, the quantity of seed. 



lllustration.s. — 1°. Mr. Pusey observed that the increase of his wheat 

 crop, on the Oxford clay, where nitrate of soda was applied, arose from 

 there being no underling straws with short ears as in the undressed, but 

 all were of equal length and consequent fullness and ripeness. The 

 nitrate had merely promoted the growth. (See Royal Agricultural Jour- 

 nal, IL, p. 120.) 



2°. "It affected the tops of the potatoes, but the produce of bulbs was 

 less both by weight and measure" (Mr. Grey, of Dilston). "On peas, 

 in a thin sandy soil, subsoil gravel, it had much effect on the colour and 

 strength of the stems, and on the state of forwardness, but when ripe, 

 though the straw was stronger, there was no diflTerence in the crop of 

 peas" (Colonel Campbell, of Rozelle). " On land in high condition it 

 did harm by forcing the straw at the expense of the ear" (Mr. Barclay). 

 " It appeared to act strongly, and there was a greater bulk of straw, but 

 the increase of grain was only 50 lbs. per acre" (Sir Robert Throckmor- 

 ton). In another experiment of Mr. Barclay's the straw was vei^ strong, 

 and much of the wheat laid, but the undressed sold for 4s. a bushel more, 

 and there was no profit. 



In all these cases the nitrate promoted chiefly the growth of the stem, 

 or the production of woody fibre. The inferior quality of the grain and 

 yield of flour was owing to this action. The grain was enveloped in a 

 thicker covering of the woody matter which forms the skin or bran. 



3°. " The turnips after the nitrated wheat are decidedly better, the lops 

 are still growing and luxuriant, while on the other part they are begin- 

 ing to fall" (Hon. H. Wilson). They seem, therefore, in some cases, at 

 least, to prolong the growth. 



From the above statements we seem to derive an explanation why the 

 effects of the nitrate should have been so universally observed upon the 



