nessee rock phosphates are the standard basic materials from which 

 superphosphates are mainifactured. 



Tliere are also high-grade potash fertilizers. Among these are 

 the German potasli salts, which may be depended upon to give a 

 fairly constant percentage of potash. The above and other nitro- 

 genous, phosphatic and potassic compounds are worked over by the 

 manufacturer of commercial fertilizers, and form what we com- 

 monly know as commercial fertilizers. 



The different food elements should not he expected to jyerfonn 

 certain sj>ec{fic things in the huilding up of the plant. — -The ques- 

 tion is often asked, " Can I, by the use of certain fertilizers, accom- 

 plish certain definite results ? " It is unwise to give any such assur- 

 rance. It may be safe to generalize somewhat as follows : 



Nitrogen. — If nitrogen is used in excess it is more than prob- 

 able that a luxuriant growth will result. If the orchard, therefore, 

 is making plenty of wood, and is carrying healthy foliage, this would 

 suggest that nitrogen, as a special fertilizer, was not needed. If, on 

 the other hand, the growth is meagre and stunted, an application of 

 some material containing nitrogen in excess might be expected to 

 give good results. The eifect of fertilizers is not always seen on 

 trees the lirst or even the second year of their application. The 

 results may follow two or three years later. This will depend, of 

 course, in a measure on the nature of the fertilizer used. If, like 

 nitrate of soda, it is immediately available, then results may be 

 looked for sooner than if it is of the nature of barnyard manure 

 which can only be used by the plant after thorough decomposition 

 has taken place. 



Potash. — This fertilizing constituent is always looked upon by 

 fruit-growers as being very important. It is well to remember that 

 tillage increases the amount of available potash in the soil. The 

 principal sources of potash are the German potash salts, chief among 

 which are kainit, nniriate of potash and sulfate of potash. An 

 available form of potash is that found in unleached, hard wood 

 ashes. These should contain from four to eight per cent of potash, 

 the amount depending upon the wood from which the ashes were 

 derived and the way in which they were kept. 



397 



