62 2 



Journal of Agriculture. Yicforia. 



[lo Oct.. I 91 j. 



Lime and Nitrification. 



Lime is important in the production of nitrates. Wliere land show.s. 

 signs of being " run down "or exhausted in fertility, this is more frequently 

 due to its failure to produce sufficient nitrates than to anything else. 

 Additional superphosphate manure will not help this, because if nitrates- 

 are deficient, extra phosphates given will not remove the defect. Lime- 

 does not contain nitrates, but it causes a m.ore rapid production of nitrates 

 from the supply of organic nitrogen within the soil. 



The organic nitrogen in soils is not in a form which the crop can; 

 utilize. It is converted into the nitrate form by different kinds of bacteria. 

 The changes may be viewed in two stages. The first stage results in 

 the formation of ammonia from the organic matter ; the second stage results 

 in the conversion of the ammonia into nitrates. 



First Stage of Nitrification. 

 The first stage may be considered first. When fresh vegetable residues 



are incorporated in the soil, this kind of organic matter yields ammonia 



]. With lime. 2. Cuiitrul Ulaiik. 3. With gypsum, i. Witii cai Ijuiiatc ut limr. ' 

 FIG. 2. SHOWING HOW LIME HELPS NITRIFICATION. 



with comparatixe ease. Where land has been long under cultivation without 

 any return of fresh organic matter, the production of ammonia becomes- 

 each year a matter of greater difficulty. As it gets older, the soil organic 

 matter gets " tougher," and the fir.st stage in nitrate production, viz., the 

 production of ammonia, becomes, in consequence, more difficult. 



Lime helps the change. Ammonia is a product of the decomposition 

 of soil organic matter, but it is onlv the last link in a chain of complex 

 intermediate products. Except under specially favorable circumstances 

 a certain amount of acidity is developed in these intermediate bodies, and 

 where there is no lime as carbonate to neutralize the acid produced, the 

 activity of the bacteria producing ammonia is greatly hindered. Bacteria 

 cannot flourish when the reaction passes from neutral to acid, and when 

 the acidity becomes marked, the decay processes are left to noxious fungi 

 and moulds, which prefer an acid medium. Carbonate of lime by neutral- 

 izing the acid incidentally formed in the decav of soil organic matter, thus 

 .stimulates the production of ammonia from the relatively large supply of 

 inactive organic nitrogen which all soils possess. 



