132 Journal of ArjrioiJhire, Victoria. [11 March, IDIS. 



of the decaying vegetable matter would thus be brought to the surface, 

 and this is most undesirable. 



The Trifolium (Medicago) seedling shown in Plate 154 has been 

 chosen to illustrate iho nodules on the roots of leguminous plants, and 

 shows that they commen'-e to delevop as soon as the roots have extended 

 a short distance from their base, and how they subsequently multiply. 

 This is a photograph (natural size) of the specimens it depicts. The 

 seedling was seventeen days old when removed, with its roots intact, 

 from the box of sandy soil in which it was grown. The nodules shown 

 in the illustration, and marked (a) and (h), were cut from a plant of 

 the same variety eight weeks old. 



As the complete change from the growing plants into the decomposed, 

 and subsequently nitrified and soluble form, as food for the trees, occupies 

 a considerable period, no time should be lost in ploughing the peas 

 under as soon as they have collected their maximum of cell sap and 

 completed their nodule development. Especially on poor soil, the crop 

 should be enabled, by the assistance of artificial fertilizers — super- 

 phosphate, bone dust, or nitrate of soda — to commence growth in early 

 autumn, and be sufiiciently matured for turning under in early spring. 

 Provided this phase of green manuring be treated with the promptitude 

 which its importance demands, the orchardist may reasonably assume 

 that the chemical changes necessary to render the soluble nitrates avail- 

 able for his trees will have commenced by the time the trees have beguii 

 vigorous growth, and will contiiuie afterwards to supply the food for 

 fruit development. 



A most interesting article on the " Mtrification of Organic Manures." 

 by Jno. W. Paterson, B.Sc, Ph.D., formerly experimentalist, and P. K. 

 Scott, Chemist for Agriculture, was published in the Journal of Agricul- 

 ture, June, 1914. 



The article deals, under various headings, with the different forms of 

 nitrogen, production of nitrates, production of ammonia, action of soil 

 bacteria, conditions influencing ammonification, and rate of ammonifi- 

 cation, (fee. Tabulated results of tests made in the laboratory are also 

 given in detail. 



Plate 155 was employed to illustrate the article, which, however, is 

 too long to permit of its being reprinted in full here, but the writer 

 regards as an interesting and instructive compendium the authors' 

 summary, which is as follows : — 



1. ISTitrogen exists in soils and manures in three forms. 



2. Nitrate nitrogen is required by plants. 



3. Ammonia nitrogen is the raw material for producing nitrates. 



4. Organic nitrogen is the raw material for producing ammonia. 



5. Bacteria change ammonia into nitrates. 



6. Another kind of bacteria change organic nitrogen into ammonia. 



7. Animal and vegetable manures contain their nitrogen as organic 



nitrogen. 



8. Their rapidity of action depends, in the first place, upon the 



rate at which their nitrogen is converted into ammonia. 



9. In any case, the change is gradual, and requires time. 



10. Lime hastens the change. 



11. A sufficient soil moisture hastens the change. 



