6 



favouring nitrification, lime or chalk is the one that is most fre- 

 quently lacking in practice and that merits the careful consideration 

 of every agriculturist who seeks to obtain the best returns from the 

 cultivation and manuring of his land. Chalk is rapidly washed out 

 of cultivated soil through the action of water and carbonic acid, and 

 moreover it is an essential for the working of sulphate of ammonia at 

 two stages of its history in the soil. First, chalk is required to con- 

 vert the sulphate into carbonate of ammonia, and again when this 

 ammonia is undergoing oxidation through the agency of the ' nitroso* 

 bacteria, cbalk (or under certain conditions magnesium or potassium 

 carbonate in its place) is essential for the production of the nitrite. 



It is difficult to draw a hard and fast line as to the minimum 

 amount of chalk in a soil for the adequate nitrification of ammonia. 

 From the theoretical point of view, an acre of loamy soil to a depth of 

 6 inches woxJd lose about 95 lbs of lime (previously existing as car- 

 bonate) for each hundredweight of sulphate of ammonia applied to the 

 soil. This spells a theoretical minimum of one part of lime in 20,0U0 

 parts of soil for the nitrification of 1 cwt. of sulphate of ammonia per 

 acre. A soil containing such a small proportion of lime as this how- 

 ever, would be practically sterile, and it would appear that soils which 

 prove capable of free nitrification and adequately respond to the appli- 

 cation of a liberal manuring contain, as a rule, at least a hundred times 

 this amount of lime (0 • 5 per cent.) 



At the same time, there are hundreds of soils containing as little as 

 1 part in a thousand of lime (0.1 per cent.) in which ammonia or dung 

 prove capable of normal nitrification. 



The results of soil analyses are frequently misleading on this point, 

 as the analyst often gives his results for the total lime in every form 

 of combination in the soil and neglects to state the proportion of lime 

 as carbonate which is alone of service in assisting the efficacy of sul- 

 phate of ammonia Many of the cases on record in which chemical 

 fertilizers have failed to produce adequate results ha e been due to a 

 deficiency of chalk in the soil. Such a failure would as inevitably 

 follow the use of dung, guano, or dried blood and is the outcome of a 

 fundamental deficiency in soil fertility 



In emphasizing the great necessity of chalk in the soil for the suc- 

 cessful use of ammoniacal manure, we are but urging a matter of cru- 

 cial importance as regards the general fertility of the soil. 



Chalk is a necessary foundation of the fertility of the soil. 



In its absence, sulphate of ammonia cannot be nitrified, dung and 

 organic manures are incapable of normal results and acid phosphates 

 or potash salts become ineffective or even injurious manurial applica- 

 tions. 



The surprising results which have been obtained on many soils by 

 the use of basic slag are largely due to its alkaline nature and the as- 

 sistance it re ders to the progress of nitrification in the soil. 



Liming.— li lime be a necessity for the progress of nitrification, and 

 its constant wasting from the soil a necessary result of cultiiral condi- 

 tions, its addition to soils in need of it. is clearly a matter of some mo- 

 ment. The practical solution of the lime problem is not as simple as 

 it appears at first sight. Lime is itself a powerful and caustic sub- 



