FIELD EXPERIME>fTS OS MAVUBE CONSTITUENTS. 161 



Troduce per acre. Increase per acre. 



J^'ot- Manure. tons. cwt. qrs. lbs, tons. cwt. qrs. lbs. 



3. 3 cwt. of superphosphate 17 11 2 10 ... 2 17 1 6 



4. ] cwt. of superphosphate 27 6 3 4- ... 2 12 2 



5. 6 cwt. of superphosphate 21 2 3 12 ... 6 8 2 8 



6. 3 cwt. of gypsum 16 H 1 4 ... 2 



7. 2 cwt. of superphosphate and 1 cwt. 



of Peruvian guano 18 11 1 20 ... 3 17 6 



8. 3 cwt. of Peruvian guano 18 17 2 20 ... 4 3 1 16 



9. 1 cwt. of sulphate of ammonia ... 15 17 3 12 ... 1 3 2 8 



10. No manure 14 14 1 4 ... 



11. 3 cwt. of fine bone-dust 18 9 2 16 ... 3 15 1 12 



12. 2 cwt. of sulphate of ammonia ... 16 17 3 12 ... 2 3 2 8 



13. 3 cwt. of turnip manure 20 1 1 20 ... 5 7 16 



14. 1 cwt. of nitrate of soda 18 9 1 4 ... 3 15 



15. 6 cwt. of turnip manure 20 7 16 ... 5 12 3 12 



16. 3 cwt. of common salt 15 16 1 ... 1 13 24 



17. 3 cwt. of dissolved bone-ash 20 15 2 24 ... 6 11 20 



18. 3 cwt. of dissolved bone-ash and 



1 cwt. of sulphate of ammonia 20 6 3 24 ... 5 12 2 20 



19. 3 cwt. of sulphate of potash 17 2 4 ... 2 6 1 



20. 3 cwt. of dissolved bone-asii and 



1 cwt. of nitrate of soda 21 2 4 ... 6 6 1 



In looking over the list of the different manures employed in these experi- 

 ments, it will be noticed, in the first place, that certain simple salts which 

 commonly enter into the composition of artificial manures have been used 

 separately. It is not likely that we shall ever understand the action of com- 

 plicated manures if we do not carefully study the separate effect of their 

 component parts on vegetation. For this reason one plot was manured with 

 sulphate of ammonia, another with sulphate of lime, a third with sulphate of 

 potash, a fourth with chloride of sodium, and, finally, one with nitrate of soda. 



In the next place, we have in Plot 17 phosphates chiefly in a soluble con- 

 dition, and free from organic matter or anything else but sulpliate of lime, 

 which is necessarily produced when bone-ash is treated with sulphuric acid. 

 In another plot (No. 18) we have the same materials in conjunction with 

 sulphate of ammonia ; and in No. 20 we have them united with nitrate of 

 soda. Then with respect to the form in which the nitrogen is applied in 

 these experiments, I would observe that we find it in farm-yard manure, 

 partly as ready-formed ammonia, partly in the stage of semi-decomposed 

 nitrogenized organic matter. In sulphate of ammonia it exists of course as 

 a salt of ammonia; for nitrate of soda, v/e apply nitrogen in the shape of 

 nitric acid. In guano nitrogen exists, partly, only in tlie form of ammoniacal 

 salts,— the greater portion of nitrogen being present as uric acid and other 

 organic compounds, which readily yield ammonia on decomposition. And 

 lastly, we have all these different forms in which nitrogen can be conveniently 

 applied to the land combined, together with phosphates, in the turnip manure. 



The results of these experiments, though unsatisfactory in some respects, 

 are nevertheless interesting and suggestive in others, and worthy of some 

 comments. 



Plot 1. Manured witli 15 tons of farmyard manure per acre : — 



tons. cwt. qrs. lbs. 



Produce 18 10 2 24 



Increase 3 16 1 20 



Plot 2. Manured with 15 tons of farmyard manure and 2 cwt. of super- 

 phosphate per acre : — 



1861. j^ 



