6 Experiments upon Swedes. 



to a successful issue, simply, I believe, because we are unac- 

 quainted with the precise circumstances under which ammonia 

 exerts a beneficial or contrary action upon root-crops. The ques- 

 tion of the superiority of guano or superphosphate mainly hinges 

 upon this : Can I dispense with the expensive ammonia, and yet 

 get a good crop of roots ? I have no hesitation in saying that 

 there are many soils upon which excellent root-crops may be 

 grown without the direct application of ammoniacal manures, and 

 that at the present time a great deal of ammonia, the most expen- 

 sive constituent of guano, is, comparatively speaking, lost, and 

 therefore guano itself to a great extent wasted, in the cultivation 

 of turnips. 



In support of these assertions, I may mention the fact that 

 phosphatic guanos that are comparatively poor in ammonia, such 

 as Saldanha-bay or Ichaboe, have been found to yield much 

 larger crops of turnips than Peruvian guano, which contains a 

 great deal more ammonia; likewise the fact that a mixture 

 of superphosphate and guano generally answers better than guano 

 alone. Again, I may mention that excellent crops of turnips are 

 now grown every year, which are manured with nothing else but 

 superphosphate, made exclusively from bone-ash or mineral 

 phosphates. 



It is, indeed, worthy of notice, that at least 90 per cent, of all 

 the artificial manures that are now offered for sale, whatever their 

 name may be, are in reality superphosphates, and that most of 

 these manures contain either no appreciable amount of nitro- 

 genized matters, or, at any rate, are very poor in nitrogen or am- 

 monia. It is not likely that an intelligent class of men like the 

 manufacturers of artificial manures, would shorten the supply of 

 nitrogenized or ammoniacal matters in turnip manures, if they 

 had not found out by experience that they can give more satis- 

 faction to the farmer by supplying him for his turnips with a 

 manure rich in available phosphates and poor or destitute of 

 nitrogen, than by sending manure poor in phosphates and con- 

 taining much ammonia. 



It is certainly remarkable that, in nine cases out of ten, even 

 those artificials, which, like iiitro-phosphate, ammonia-phosphate, 

 blood-manure, &c., convey the idea of manures rich in nitrogen 

 or ammonia, when prepared for turnips, hardly contain any ni- 

 trogen. Still I am informed, on good authority, that there are 

 many soils on which the very cheapest manure that can possibly 

 be used for turnips is guano. 



How can these contradictory facts be reconciled? I believe 

 only when the subject is thoroughly investigated, without direct 



