BEHAVIOUR IN THE SOIL 



23 



Some experiments by \Yagner (Forschungen atif dcm 

 Gebicte der Pflanzenernahrung, 1892, 440) will serve very 

 well to illustrate the influence of the various conditions just 

 mentioned on the nitrification of sulphate of ammonia. We 

 shall quote only the experiments made with the smallest 

 proportion of ammonia salts, 0^471 gram added to 300 grams 

 of soil. This quantity was, however, far beyond anything 

 that is employed in agriculture, amounting in fact to 28 cwts. 

 per acre, if the surface soil is reckoned as weighing two 

 million pounds, corresponding to a depth of about 7 inches. 



Wagner used two soils. The poor loam contained 18 per 

 cent, of water. The garden soil, richer in humus, contained 

 30 per cent of water. Each soil was used alone, and also 

 with the addition of 1*6 per cent of marl. The experiments 

 were made both in a cold and warm room. A considerable 

 number of mixtures were made in each series of experiments, 

 and the nitric acid present was determined every twelve 

 days in one lot in each series. To give the results a practical 

 bearing, we have expressed them as pounds of sulphate of 

 ammonia nitrified per acre. The figures in the table show 

 in a very striking manner the immense influence which mois- 

 ture, temperature, and the presence of an ample supply of 

 carbonate of lime have on the rate of nitrification of sulphate 

 of ammonia. 



TABLE III. 



POUNDS OF SULPHATE OF AMMONIA NITRIFIED PER ACRE 



UNDER VARIOUS CONDITIONS (WAGNER). 



