178 



Nitrification. 



It must be borne in mind that all of the above fertilisers, save ni- 

 trate of soda, must be decomposed and converted into soluble forms be- 

 fore they can be appropriated as plant food This process of conver- 

 sion is usually denominated as " nitrification." 



Nitrification must go on in every cultivated soil in order that plants 

 may grow therein, and the more rapid this nitrification ceteris pari' 

 bus/' the greater the growth of the plants in a given time. The pro- 

 cess of nitrification is accomplished through the work of micro-organ- 

 isms (bacteria) of which there are three different types : 1st, those 

 which convert nitrogenous matter into ammonia ; 2nd, those which 

 convert ammonia into nitrous acid, and 3rd, those which convert ni- 

 trous acid into nitric acid. Each of these is necessary to the com- 

 plete transformation of cotton seed meal, dried blood, tankage, etc., into 

 nitric acid, the form of nitrogen chiefly available as plant food. 



It should be the aim of every cultivator to maintain his field in 

 conditions most favourable to the development of these soil ferments, 

 upon whose activity,not only the plant food already in the soil, but also 

 that applied in the form of fertilisers, depend for their solubility. The 

 conditions for the rapid multiplication of these ferments are given in 

 the chapter on cultivation. It will be apparent, however, from the 

 above, that it is a misuse of fertilisers to apply them to soils that have 

 been badly ploughed, imperfectly drained, and in bad tilth. Every 

 planter, before resorting to the use of fertilisers, should see that the 

 fioil upon which they are to be applied should be in a condition to aid 

 in the most rapid nitrification possible. Only by the observance of 

 conditions most favourable to nitrification, can the full effects of the 

 applied fertiliser be obtained. (*) 



NITROGEN REQUIRED IN A ROTATION. 



From investigations made by this station, a crop of cow peas when 

 turned under at the propar time, will add at least 100 pounds of nitro- 

 gen per acre, most, if not all of which, it is believed, is gathered from 

 the air. (^). The average crop of plant cane grown upon pea vine 

 land is not far from thirty tons per acre. The first year stubble fol- 

 lowing this plant, should give twenty tons per acre, and if kept for 

 the second year stubble, a crop of at least 15 tons per acre should be 



(4) These modern vidws which regard the soil as a complex workshop, full of 

 living organisms busy preparing nitrogenous matters in order to fit them for the 

 use of plants, have don© perhips more than anything else to place agriculture oa 

 a scientific basis ; we now know why it is that tillage and drainage are such im- 

 portant factors and why if they are neglected poor crops are obtained even when 

 an abundance of plint food is present in the soil. It will be seen that most agri- 

 cultural operations are directed towardj maintaining the s )il in such condition 

 that the nitrifying bacteria may best flourish in it ; this being accomplished, good 

 <;rops may be expected. — F. W. 



(5) This use of green dressings is of the first importance to sugar growers. Thi 

 100 pounds of nitrogen is equal to about 500 pounds of Sulphate of ammonia 

 so that a green dressing in addition to improving the texture of the soil and add- 

 ing humus to maintain this improved condition, draws from the atoaosphere up- 

 wards of £3 worth of nitrogen per acre and adds it to the soil in ft condition 

 suited to the requirements of the sugar cane. — F. W. 



