FERTILIZERS FOR VEGETABLES 227 



course it is diluted in that case. I should advise wholly 

 against anybody attempting to use cyanamid alone except in 

 an experimental way, and then with a good deal of caution. 

 Where it is used with precautions along with other plant- 

 food materials, it has been found to give on general field 

 crops about as good results as ammonia nitrogen. It is real- 

 ly an ammonia compound. When it is put into the soil and 

 becomes moist, it changes into ammonia. Under certain 

 conditions another compound may be found, which is known 

 by the name of dicyanamid, and that is very poisonous. 



For Onions. 



A Member: I would like to have your formula for fer- 

 tilizer on muck for onions. 



Professor Van Slyke: It would be practically the same 

 as I gave for lettuce. That is a good formula for vegetables 

 in general. With reference to the onions, I should be in- 

 clined to use somewhat less nitrate of soda, perhaps a third 

 nitrate of soda, and a third sulphate of ammonia, and the 

 rest meat tankage, or perhaps a third nitrate of soda and the 

 balance meat tankage. You do not want to force the onions 

 too rapidly. In regard to the potatoes, use about the same. 

 So far as formulas are concerned, it is not so much, in my 

 judgment, the particular proportions that you put on as it 

 is the total amounts that you put on; and the main thing is 

 to be sure that you have enough of the different forms of 

 plant-food. 



For Potatoes. 



Question: How much on an acre of potatoes on sandy 

 soil? 



Professor Van Slyke: With reference to potatoes, I 

 should recommend on a soil that has been well handled and 

 that is known to contain considerable amounts of organic 

 matter, whether from manure or from green crops turned 

 under, a fertilizer containing not perhaps more than one- 

 fourth of its nitrogen in the form of nitrate of soda and per- 

 haps one-fourth in the form of sulphate of ammonia, and the 

 balance in the form of meat tankage. In the case of a soil 



