10 DEPARTMENT OF AGRICULTURE. 



to deep-rooted plants and the nitrate of soda to shallow-rooted plants. Unless the 

 soil to which they are applied contains a high lime content the frequent use of 

 ammonium sulphate will make a soil acid. 



Nitrate of soda should never be mixed with acid phosphate before applying to 

 the soil. A chemical action takes place if this is done that results in a considerable 

 loss of nitrogen. It is preferable to apply the acid phosphate six or seven weeks 

 before the date of planting and the nitrate of soda not more than a week before 

 planting. 



All the chemical nitrogen fertilizers are readily available; consequently they 

 should be applied in small quantities shortly before they are required by the plants, 

 otherwise the nitrogen in the form of nitrates will dissolve and leach away. 



Calcium nitrate and calcium cyananiide are as valuable as the first mentioned 

 if their value is based upon the percentage of nitrogen they contain. Calcium 

 cyananiide should be applied shortly before seeding, for it is considered to have a 

 slightly toxic action on vegetable-growth. More recently claims have been made that 

 the toxic materials contained in the fertilizer have been successfully removed. 



Nitrogen is an important element to consider in the study of fertilizers. 

 Nitrogen usually costs about three times as much as phosphoric acid. This fact 

 serves to emphasize the necessity of maintaining the nitrogen-supply in soils by the 

 use of clover, alfalfa, and other legumes rather than by the application of nitrogen 

 in the form of a commercial fertilizer. 



PHOSPHATIC MANURES. 



A number of materials are used as a source of phosphoric acid. The principal 

 sources are listed in the following table : 



(a.) RAW PHOSPHATES. 



Nitrogen. 



Per Cent. Per Cent. 



1. Raw bone-meal ......................... 19-25 2-4 



2. Steamed bone-meal ..................... 17.5-29 5-4.5 



3. Bone-black ........ ..................... 30 



4. Bone-ash ...... . ....................... 30-39 



5. Bone-tankage .......................... 11.5-20 4-6 



6. Dried ground fish ...................... 6-16 4-11 



7. Phosphatic guanos ..................... 11-42 



8. Basic slag ............................. 11-13 



9. Ground rock phosphate ................. 25-40 



(6.) SUPERPHOSPHATES. 



Total Available 



Phosphoric Acid. Phosphoric Acid. 

 Per Cent. Per Cent. 



1. Acid phosphate .................... 14-18 12-16 



2. Dissolved bone-black ....... . ...... 16.5-17.5 12.5-16.5 



3. Double superphosphate ............ 48 43 



RAW PHOSPHATES. 



The organic phosphatic manures, the first seven in the above table, are very 

 variable in composition. 



Raw bone-meal is a finely ground product derived from raw bones. It carries 

 considerable organic matter in the form of fats. This fatty organic matter tends to 

 make the fertilizer very slowly available as plant-food. The phosphoric acid in 

 steamed bone-meal is more available than bone-meal, for in the manufacturing 

 process the fats are extracted. Grinding does not affect the composition but finely 

 ground material is more available than coarser samples. 



Bone-black, a by-product of sugar-refineries consist of bones that have been 

 heated and distilled until all the organic or volatile matter has passed off. The 



