11 March, 1918.] Apple Culture in Victoria. 



133 



12. The rate of change depends also very largely on the class of 



manure. 



13. Bone and blood may have four-fifths of their nitrogen rendered 



available in four months. 



14. Quickly-acting manures are soonest exhausted. 



15. Half the nitrogen in lucerne may be rendered available in four 



months. 



16. Very heavy dressings of fresh stable manure, as in the garden, 



may be worse than useless by destroying any nitrates pre- 

 sent. 



17. This danger will be most prominent on land Avhich is fairly wet, 



and in wet seasons. 



18. A moderate dressing of stable manure Avill yield nitrates 



gradually, and with good result. 



19. Leather, horn, hoofs, and wool waste in mixed manures will show 



nitrogen on analysis, but they will be slow in action. 



20. In purchasing manures of organic origin, it is particularly neces 



sary to know the source from which their nitrogen is 

 dorivod. 





*Plate 155. — Bacteria which Change the Nitrogen in Soils (highly magnified). 



(a) Producing nitrites from ammonia ( Winogradsky ) . 



( h ) producing nitrates from nitrites ( Winogradsky ) . 



(c) Producing ammonia from organic nitrogen — A. Bac-mycoides; B. Bac- 

 stutzeri ( Conn ) . 



The Influence of Lime. 



Lime has an important influence on most orchard soils; it helps to 

 make heavy soil more friable, and, besides supplying practically essential 

 plant food, assists in freeing unavailable phosphates and potash. It 

 also enables the changes in manures containing the crude forms of plant 

 food to commence earlier and pass m^ore rapidly through the successive 

 variations by which its ingredients are converted into the soluble form, 

 and thus made available to the feeding roots. Generally speaking, sandy 

 soils do not need lime to the same extent as clayey or peaty kinds, for 

 the reason that the latter, when they become deficient in lime as a plant 

 food, also acquire an acidity, or sourness, that renders them 

 unfavorable to the growth of fruit trees. Virgin soils usually contain 

 lime in sufficient quantities to enable the trees to grow and fruit satis- 

 factorily for some years after being planted. But when the original 

 supplies of plant food have become depleted through continuous 



These illustrations are taken from Hihjurd on Soils. 



