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EXPERIMENT STATION RECORD. 



At the Ijcgiiming of the pot experiments with the soil used in this 

 investigation muriate of potash was applied at the rate of 7.36 gm. and 

 dissolved boneblack at the rate of 22.07 gm. per pot in every case. 

 These amounts Avere afterwards increased to 10 and 25 gm. respectively. 

 In different cases ammonium sulphate and nitrate of soda were applied 

 in amounts furnishing- 2.6.5 gm. of nitrogen per pot. Where lime was 

 used the maximum amount applied was 147.2 gm. per pot (4 tons per 

 acre). Gypsum was also applied in some cases at rates furnishing the 

 same amount of calcium oxid as the lime. The results of the deter- 

 minations of humus and nitrogen are given in the following table: 



TJie infiuenre of lime and other siihMances on the humus and nitrogen content of soils. 



FertilizatioTi. 



rnmannrerl 



Ammonium sulphate 



Ammonium sulphate, air-slaked lime (1 ton per acre) 



Ammonium sulphate, air-slaked lime (4 tons per acre) 



Ammonium sulphate, calcium sulphate (land plaster) at rate cquiva 



lent in CaO to 4 tons of air-slaked lime per acre 



Without nitroffcu and lime 



Air-slaked lime ( 4 tons per acre) 



Nitrate of soda 



Nitrate of soda and air-slaked lime (4 tons per acre) 



Humus 



nitrogen 



in dry 



soil. 



Per cent. 



0.130 



.128 



.133 



.120 



.139 

 .129 

 .139 

 .143 

 .133 



Humus 



in dry 



soil. 



Per cent. 

 3.86 

 3.93 

 3.77 

 3.63 



3. 0.=) 

 3.75 

 3.51 

 3.93 

 3.42 



Nitrogen 

 in dry 

 humus. 



Per cent. 

 3.37 

 3.26 

 3.53 

 3.47 



3.81 

 3.44 

 3.68 

 3.64 

 3.89 



"From the foregoing it will be seen that without exception the addition of air- 

 slaked lime or gypsum resulted in lowering the total amount of humus, as compared 

 Avith the unmanured plat, yet in every instance the jjercentage of nitrogen in the 

 humus had been increased. In fact, the latter statement applies also even where no 

 nitrogen was added. 



"Where lime was not applied, but nitrogen was employed in form of sulphate of 

 ammonia, which in the acid soil proved poisonous to plants, it will be ol)served that 

 the percentage of nitrogen ui the humus was even less than where no manure was 

 used. On the contrary, where nitrogen in the form of nitrate of soda was added 

 without lime, the percentage of nitrogen in the humus was greater than in the case 

 of the unmanured soil. 



"It is also of special interest to observe that in the case of the unlimed soil which 

 received potash and phosphoric acid but no nitrogen, the percentage of humus 

 became less than in the unmanured soil; while, on the contrary, where nitrogen was 

 applied as nitrate of soda and as sulphate of ammonia to unlimed soil, it is i^ossible 

 that a slight increase in the percentage of humus resulted. The differences are not 

 great enougli, however, to furnish any positive evidence in this respect." 



The causes and the importance of the decomposition of nitrates 

 in soils, W. Kruger and W. Schneidewind {Landw. Jahrh.^ 29 

 {1900)., No. Jf-5., j)P- '7p-770, pin. 2). — In continuation of previous 

 investigations, the authors report pot experiments to determine the 

 action of various kinds of carbonaceous materials and the effect of 

 well-rotted and fresh mixtures of manure and litter on the activity of 

 the denitrifying organisms, as well as ffeld experiments on denitrilica- 

 tion, comparing the results by the 2 methods, and discus.sing the inffu- 



