Normal Soil and Its Requirements 17 



these are very expensive and reduce the net profit 

 from the crops. The object of every intelligent 

 trucker should therefore be to reduce his manure and 

 fertilizer bills by encouraging his soil bacteria to man- 

 ufacture the greatest amount of the available food 

 which his crops require. Like any other living form 

 these bacteria require certain conditions of life if they 

 are to thrive. 



MAINTAINING THE NITROGEN SUPPLY 



The nitrifying bacteria are air-loving organisms. 

 Hence the more aeration we give them, the more pro- 

 nounced their activity. Schlosing 1 determined that 

 when a soil was entirely void of oxygen the nitrates 

 were reduced, and brought about an actual evolution 

 of free nitrogen which is useless to the plant. With 

 1.5 per cent, of oxygen nitrification was marked. 

 When 6 per cent, oxygen was added to the soil nitri- 

 fication was more than doubled. It is therefore 

 evident that cultivation which aims at soil aeration 

 also accelerates nitrification. The effect of soil 

 aeration cannot be too strongly emphasized. Ac- 

 cording to Chester, 2 every cultivation of the soil 

 with its attendant aeration is equivalent to a dressing 

 of nitrate of soda in its cheapest form. If we realized 

 this, and that nitrate fertilizers are usually the most 

 costly, the alert trucker would learn the economy of 

 more cultivating. 



1 Schlosing, Compt. Rend. Acad. Sci. Paris, Ixxvii, 203-253. 

 Chester, F. D., Pa. State Dept. of Agr. Bid. 98: 9-88, 1912. 



