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sion of the organic matter of a soil into nifates is the result of the life 

 functions of two organisms — the one a purely nitrous ferment, i.e., capa- 

 ble only of oxidizing ammonia and nitrogenous humus to nitrites and 

 not to the fully oxidized form o{ nitrates, the other, known as the nitrite 



ferment, whose function it is to convert nitrites into nitrates. This 

 nitric organism completes the useful work of nitrification. By an 



immence amount of bacteriologic.il study Mr. Warington at last suc- 

 ceeded in isolating, growing and photographing this highly interesting 

 plant. He says, "in soil, both organisms are present in enormous 

 numbers and the action of both organisms proceeds together as the 

 conditions are favourable to both." Denitnfication or the destruction 

 of nitrates takes place in water-logged soils from which the air is 

 necessarily excluded. This is brought about through the agency of 

 a third living organism, and the conditions most favourable for its 

 development are an absence of oxygen, and an abundant supply of 

 readily oxidizable organic matter. The practical lesson from this 

 conclusion is the necessity of well-drained land, in order that the 

 surplus water may be carried off and the air allowed to freely permeate 

 the soil. 



The nitrates are developed in the upper layers of a soil, but being 

 extremely soluble are washed down by heavy rains to the subsoil. 

 Ploughed land, well drained, loses nitrates when not cropped, and more 

 so especially in wet seasons. Bare fallow does not, therefore, entail an 

 unmixed good. In this connection Mr. Warington says, " If a farmer 

 could ensure dry seasons, so that the nitrates produced by a bare fallow 

 should remain in the soil available for the succeeding crop, it would 

 pay him better to have an alternation of wheat and bare fallow rather 

 than to grow wheat continuously. However, in the English climate no 

 such favourable results ca.i be expected," as the results of 30 years' 

 experience at Rothamsted have shown that " wheat after fallow, except 

 in some of the earliest years, has not given the double produce which 

 should result from the presence of a double supply of nitrates." By a 

 system of drain gauges Mr. Warington has been able to measure this 

 loss of nitrates. He says, " The average quantity of nitrogen as nitrate 

 discharged from the soil during thirteen years has been for the 20-inch 

 gauge 37.3 lbs , for the 40-inch gauge 32.6 lbs,, and for the 60-inch 



