82 REMARKS UPON PRECEDINa EXPERIMENTS. [AppeTldix, 



and urine mixed with charcoal and gypsum, and dried by a gentle heat. Its ef- 

 fects upon the wheat crop are, in the present experiments, more favourable than 

 any of those I have yet placed upon record. The following experimental re- 

 sults exhibit the nature of its action in two localities, both in the seune neigh- 

 bourhood : — 



Undressed. Dressed. Experiments made at 



Wheat ... 44 bush. 51 bush. Erskine. 



Oats .... 49 bush. 45 bush. do. 



Turnips . . . 12f tons. 13| tons. Barochan. 



Do. ... 12 tons. 17 tons. do. 



Potatoes . . . ' 5| tons. lOf tons. do. 



These results, especially those upon the corn crops, are not so beneficial as 

 might well be expected from a prepared night-soil, and they affoi-d room for the 

 suspicion that the mode of manufacture has been such as to dissipate some of 

 the more valuable constituents. 



10°. Experiments upon potatoes. — In the experiments upon potatoes the whole 

 crop averaged 12 tons per acre, and the parts of the field to which the artificial 

 manures were added exhibited no marked increase above this general average. 

 Even the mixture of nitrate with sulphate of soda, which in so many other 

 cases has proved beneficial to the potato crop, in this instance produced only 1 

 cwt. of increase. 



It may be that the manure which was added at the rate of 45 tons per acre 

 contained a sufficient supply of all those kinds of food which were added after- 

 wards in the saline and other substances. If so, a larger crop could only have 

 been obtained by the addition of some other substance not tried, for a loam of 

 moderate quality ought to be able to produce more than 12 tons of potatoes per 

 acre. 



Or it may be that these same artificial manures would have produced a larger 

 increase had they been put on as a top-dressing after the crop had come up, in- 

 stead of being spread upon the manure before the potatoes were planted upon 

 it. In the experiments of Mr. Fleming made with especial reference to this 

 point, [Appendix, pp. 49 and (Jt),] it was found that a lai-ger propoi'tionate 

 iticreose was obtained from the same saline substances applied in equal quanti- 

 ties to the potato crop wJien they were spread upon the manure^ than when they 

 •were applied as a top-dressing after the crop had come up. Still the experiments 

 in his case being made in different fields, I stated that the point was not.U) be 

 considei-ed as established, but was deserving of further investigation. This 

 opinion is strengthened by the results of these experiments of Lord Blantyre : 

 I would therefore beg to offer as — 



Suggestion XIII. — That the application of saline manures to the potato 

 crop^either when the trial is made for the purpose of obtaining practical infor- 

 mation, which may, hereafter, be valuable as a guide to the operations of the 

 farmer, on the land where his experiments are made, or for that of arriving at 

 results which may be theoretically useful — that the same proportions should be 

 applied to two or more plots buried with the manure, and to two or more dusted 

 on as a top-dressing. From an accumulation of results obtained in both ways, 

 we shall be able to extract something like a principle by which practical men 

 may be easily guided in that direction which is likely in the greatest number 

 of cases to lead to the greatest amount of profit. 



11°. Water in the potatoes. — I will here add one other observation upon the 

 potato experiments. There was, as we have already remarked, no notable dif- 

 ference in the weight of crop raised upon the several patches. But the quality of 

 the crop — the weight of dry food raised upon the several patches — might really 

 be different notwithstanding. In my remarks, [Appendix, p. 65], upon the Baro- 

 chan experiments upon potatoes, made in 1842, I have drawn attenti-on to the 

 fact that potatoes sometimes contain as much as 30 per cent, of dry food, and at 

 other times as little as 20 per cent., and therefore that a ton of potatoes of one 

 kin/i wiay contain 6 cwt,, while the same weight of another contains only 4 



