3G0 EXPERIMENT STATION RECORD. 



The absence of nitrates is due to the aeid reaction of a soil contain- 

 ing an excess of vegetable matter. The nitric ferment does not act in 

 an acid medium, and this explains the great benefit derived irom the 

 use of calcareous manures. Miintz and Girard a[)i)lied to a recently 

 cleared soil of Brittany of an acid reaction dried blood, horn meal, or 

 guano, but observed no formation of nitrates until the soils were 

 marled. 



It should be observed in this connection that while it is necessary to 

 reduce the acidity an excess of soluble base is also injurious. The 

 deleterious influence of caustic lime on nitrification Avas noted many 

 years ago by Boussingault. The alkalinity of limewater, according to 

 Warington, is much more than sufficient to check the production of 

 nitric acid. Heavy liming of soil, therefore, suspends nitrification 

 until the lime is converted into carbonate, but tbe final results will be 

 favorable if the original soil is deficient in lime. 



It is true that nitrification may goon in soil deficient in lime, but wlien 

 the drainage water of such soils is examined it is found that the nitric 

 acid is combined with potash and magnesia. ^loreover, the application 

 of carbonate of lime to such soils is very beneficial and increases the 

 production of nitrates. 



A soil from Cruadeloupe gave 104 mg. of nitric nitrogen per liter 

 without application, 35.3 mg. when it received 5 gm. of sulphate of 

 ammonia, and 348 mg. when only 2 gm. of carbonate of lime was 

 added. In other words, the introduction of a small amount of lime 

 exercised as marked an effect on nitrification as a very strong applica- 

 tion of readily nitrifiable material, such as sulphate of ammonia. 



Presence of nitric ferments. — These appear to be very widely distrib- 

 uted. Miintz and Aubin have observed their jiresence not only in all 

 cultivated soils which they have examined, but also in those of deserts 

 and in those at high altitudes, such as the summit of Pic-du-Midi. 

 Warington, who has studied the dissemination of the nitric ferment 

 with much care,' found it abundant at the surface of all fertile soils, 

 but more rare in samples taken from the lower layers of the soil. In 

 a test commenced on November 17, 1883, no nitrifying organisms were 

 found below 0.9 meter of the surface. In another test made on April 

 5, 1884, the organisms Avere abundant at a depth of 0.225 meter, but 

 were not encountered at a depth of 0.375 meter. In brief, Warington, 

 in 4 observations, made at depths of 50, 75, and l.">0 mm. below the 

 surface, and in 4 experiments with culture solutions inoculated with a 

 soil taken at a depth of 225 mm., invariably found a formation of 

 nitrates. With the soil below 225 mm. the results were irregular, and 

 indicated that in clay soils the nitrifying organisms are not distributed 

 to a greater depth than 225 mm. below the surface. It is jirobable, 

 however, that they may be encountered at a much greater depth in 

 channels formed by roots; and without doubt in sandy soils they go 

 nuicli decider than in clay soils. 



^ Jotxr. Clieoi. Soc, LondoUj 45 (1886) } aba. iu Auu. Agrou., 11, p, 49, 



