526 AGRICULTURAL ANALYSIS 



The effort has been to present all the evidence which could be 

 collected, both for and against the use of ground feldspar as a 

 fertilizer. The question is still open, and systematic and long- 

 continued experimentation is the only possible method of ob- 

 taining conclusive information on the subject. The evidence so 

 far obtained appears to indicate that under certain conditions 

 and with certain crops feldspar can be made useful if it is 

 ground sufficiently fine. On the other hand, it is highly proba- 

 ble that under other conditions the addition of ground feldspar 

 to the land would be a useless waste of money. At the present 

 stage of the investigation it would be extremely unwise for 

 anyone to attempt to use ground rock, except on an experimental 

 scale that would not entail great financial loss. 



The subject must be approached conservatively, with due re- 

 gard to business economy. Sensationalism and exaggeration in- 

 variably do harm. It is extremely unlikely that ground rock 

 will ever entirely displace the use of potash salts for its availa- 

 bility must inevitably depend upon many modifying conditions, 

 such as the nature of the soil, the amount of moisture present, 

 the character of the other fertilizers used, and the varying root 

 action of different crops. With tobacco the results so far ob- 

 tained have been encouraging, but it is possible that this plant, 

 which is a voracious feeder, can make use of the potash in fine- 

 ground feldspar to a greater extent than any other fast-growing 

 crops, such as potatoes and the cereals, some of which mature 

 in practically sixty days and must therefore find their plant food 

 in a highly available condition." 



ORGANIC SOURCES OF POTASH 



446. Tobacco Stems and Waste. Until within a few years 

 tobacco stems and other waste from factories, were treated as a 

 nuisance in this country and burned or dumped into streams. 

 By burning and saving the ash, the potash contained in the stems 

 and waste is recovered in a form suitable for field use. The 

 nitrogen contained in these waste materials, both in the form 

 of nicotin and of albuminoids is lost. Ignition of this waste 

 should not be practiced. It should be prepared for use by grind- 

 ing to a fine powder. Applied to the soil in this condition the 



