BOGENHAUSEN EXPERIMENTS. 808 



12th September, 1857, the seed was sown and liarrowcd 

 in, on one day : immediately after the sowing tlicrc was a 

 moderate thunder sliower. 



The fiekl was divided into seventeen lots, each of 1900 

 square feet, which were separated from each other by 

 furrows ; each was separately sown and harrowed. The 

 quantity of guano used was 18-8 lbs. ( = 23-3 lbs. avoir.), 

 and the weight of the salts of ammonia employed was 

 calculated from the amount of nitrogen in the guano, so 

 that, as in the previous experiment, each plot received an 

 exactly equal amomit of nitrogen. The results were the 

 following : — 



Experiment in Bogenhausen. 

 Eesult of HAE^'EST, 1858 Wentee-wheat. 



Com Straw 



grammes gi-ammea 



Manured with guano, yielded 32986 79160 



sulphate of ammonia (11-8 lbs. Eav.) . 19600 41440 



„ phosphate „ (11-9 „ „ ) . 21520 38940 



„ carLonate „ (106 „ „ ) . 25040 57860 



„ nitrate „ ( 7'1 „ „ ) • 27090 65100 



Unmannred 18100 32986 



These experiments show in the clearest manner that it 

 is an error to refer the effect of a powerfid nitrogenous 

 manm-e chiefly to the nitrogen which it contains. No 

 doubt it has a share in the operation of these manures, 

 but their energy is not in proportion to the amount of 

 nitrogen in them. 



If ammonia or salts of ammonia increase the produce 

 of a field, their effect depends upon the nature of the soil. 

 What we mean here by the nature of the soil is under- 

 stood by every one ; the ammonia can engender in the 

 soil no potash, no phosphoric acid, no sihcic acid, no lime ; 

 and if these substances, which are indispensable for the 

 developement of the wheat plant, are not found in the 

 soil, the ammonia cannot produce any effect whatever. 



