No. IX.l HEMAHKS UPON PRECEDING EXPERIMENTS. 81 



yet met with, seem to point — that it is more uniformly successful when applied to 

 root than to grain crops. The increase of oats in the present experiment did not 

 exceed half a bushel per acre — though that of hay amounted to 14| cwt. 



7°. Action of sulphate of soda. — I have already noticed the effect which this 

 salt has in paling the colour of the crop, even when the produce of grass or 

 straw is increased. In regard to the grain, we see in the experiment upon oats 

 that it reduced the crop, 1^ bushels per acre — while the wheat crop was increased 

 10 bushels by a similar application. 



Is this difference in its effects due to the nature of the soil, or to the special 

 action of the sulphate upon the two crops % 



We have seen in the experiments made in 1842 at Lennox Love (p. 52), that the 

 sulphate of soda diminished the oat crop 15| bushels per acre — an effect, how- 

 ever, which may be mainly ascribed to the great drought in that locality, since 

 even nitrate of soda caused a diminution of 12^ bushels. But it also diminished 

 the wheat crop at the same place to the extent of 9^ bushels per acre, but upon 

 this crop also the drought appeared to interfere with the natural action of the sev- 

 eral top-dressings which were applied, so that no trust-worthy conclusion can 

 be drawn from the apparent results of their action. 



Suggestion XII. — I have already suggested (p. 72) an interesting experiment 

 with sulphate of soda, in order to test the very curious observation of Mr. Flem- 

 ing, that when applied to land sown with artificial grasses, it brought up a crop 

 consisting almost entirely of fescue grasses, though none of these had been 

 sown. 1 would here suggest further that the marked difference observed at 

 Erskine between the action of this sulphate upon wheat and oats should be 

 further investigated — with the view of obtaining a satisfactory answer to this 

 question — Does sulphate of soda act less favourable upon wheat than upon 

 oats in the same soil 1 Or does an unlike action manifest itself only when the 

 soils are different ^ I fear the suggestion comes too late for the present year, 

 unless, as I hope, there are' experiments already in progress which will throw 

 light upon the question. But the suggestion will not, I believe, be overlooked 

 when another year comes round. 



It is furtiier worthy of remark, in regard to the action of the sulphate of soda 

 upon the wheat crop, that the straw was stronger and less laid than where any 

 of the other dressings were applied. 



8°. Action of siUpkate of avinwnia.— The substance employed under the name 

 of sulphate of ammonia, as t stated in a previous part of this Appendix (p. 61,) 

 is not what its name implies. The makers, the Messrs. Turnbull, of Glasgow, 

 inform me that it is prepared by adding sulphuric acid to fermenting urine, and 

 evtiporating to dryness*. Though sucli a substance must vary in composition 

 with the urine from which it is prepared, and must contain more or less am- 

 'monia according to the degree of fermentation which the urine has undergone, 

 yet good effects may fairly be expected from it. I here exhibit the effect of 1 to 

 li cwt. per acre applied to different crops — 



Undressed. Dressed. Made at 



Wheat 44 bush. 54j bush, Erskine. 



Do 3U bush. 40 bush. Gadgirth. 



Oats 49 bush. 50 bush. Erskine. 



Turnips 12| tons. 24^ tons. Barochan. 



Potatoes 12f tons. I4j tons, do. 



Do 8f tons. I3i tons, do. 



These results not only recommend this substance to the practical farmer, but 

 they also enforce the remarks I have made in the text upon the value of urine 

 in general, upon the large waste of manure annually incurred by the neglect of 

 it, and upon the virtual money-loss which is suffered by those who allow it to 

 escape from their farm-yards. [See Lecture XVIII., p. 463.] 



9°. Action of Thcr-nbulVs humus. — This humus, is it is called, is night-soil 



* In the text I have described it under the name of aulphated ur»n«.— Bee p. 461. 



