180 EXPERIMENTS WITH SPECIFIC MANURES. 



surpassing- guano applied to tlie turnip-crop, it was in alliance 

 with dissolved bones and animal-cliarcoal. 



Guano, as compared with night-soil, is inferior in the 

 g-rain, and superior in the root-crops. Its merits and de- 

 merits, however, are so well known that I need not enter on 

 their detail. This far, however, I may remark, that in case 

 of the privation of this article, we have, in the case of grain- 

 cro})s, equally good substitutes in saltpetre-refuse and night- 

 soil ; and in respect of root-crops, I have no doubt that bones 

 and night-soil will be made to equal it. Eeferring to table 

 D, a curious efiect is found to follow : in the first place, 

 g'uano, saltpetre, and night-soil, in combination, and in the 

 next, the same substances with another added. The mixture 

 of the three substances is a complete failure ; with the addi- 

 tion of another substance, however, in each of three appli- 

 cations they succeed. In the first of these three applications, 

 animal-charcoal is added j in the second, sulphate of mag- 

 nesia ; in the third, nitrate of soda. The first is su])erior in 

 straw and grain, but inferior to the other two in weight of 

 g'rain ; the second is sujierior to the third in grain, but in- 

 ferior in straw and weight of grain ; and the third is inferior 

 to both the others in grain, but again surpasses both in 

 weig-ht. All, however, are very superior to the three sub- 

 stances in combination, and applied without the addition. 

 The cause of the failure in the application of the three sub- 

 stances, I cannot sufficiently explain : that it is to be attri- 

 buted to the combination of guano and night-soil, is not 

 strictly consistent with the effects of the two combined in 

 other experiments; and yet the fact, that the addition of 

 another substance is sufficient to obviate the bad effects of 

 the mixtures, seems to point in that direction. Probably, 

 therefore, the fact may be, that two ammoniacal excrements 

 operate injuriously on each other, and that they require an 

 amount of corrective power equal, on the one hand, to salt- 

 petre-refuse and sulphate of magnesia, animal-charcoal and 

 saltpetre-refuse, or nitrate of soda and saltpetre-refuse ; and, 

 on the other, to one-quarter of bones dissolved in sidphuric 

 acid. I take the facts as I find them, and these demonstrate 

 that guano and night-soil do not operate well together, 

 except when an equivalent amount of corrective power is 

 applied along- with them, or, which is to the same purpose, 

 that these substances, equally divided, of which the two 

 named are a portion, do not produce beneficial effects. I do 

 not hazard an opinion in elucidation of this subject, my 



