FERTILIZERS FOR VEGETABLES 



235 



Professor Van Slyke: I should advise the sulphate. 



Question: What form of phosphoric acid would you use? 



Professor Van Slyke: I should use acid phosphate. 

 While sulphuric acid is used in making acid phosphate, they 

 do not put in quite enough to do all the work. For example, 

 we have here a certain amount of rock to be dissolved ; it com- 

 bines with and uses up the acid. The manufacturers make 

 a point never putting in quite enough acid to dissolve all the 

 rock. They do that because they do not want to have any 

 free sulphuric acid left. If there ever is any free sulphuric 

 acid in an acid phosphate, it is very small indeed and not 

 enough to do any harm. 



Reinforcing Manure. 



Question: Do you recommend acid phosphate to put on 

 barnyard manure? 



Professor Van Slyke: Yes, as a means of holding am- 

 monia. The land plaster or sulphate of lime that is in the 

 acid phosphate combines with ammonia to some extent, and 

 the acid phosphate itself combines with the ammonia and 

 holds it as a chemical compound, so that it does not escape 

 in the air. 



Question: At what rate? 



Professor Van Slyke : Forty or fifty pounds of the acid 

 phosphate to a ton of manure. If you have muck on 

 your land that is easy to get at, just dig that out and let it 

 dry, make it fine and use that in your stable with your manure. 

 There is nothing that is quite equal to muck as a good ab- 

 sorber. It will hold the liquid, and the ammonia, and will 

 be very satisfactory. At the same time, the nitrogen that is 

 in the muck will be decomposed also. In regard to the de- 

 composition of muck, the application of organic matter — 

 stable manure or dried blood or tankage, any of those things 

 that undergo decay in the soil — helps to cause the organic 

 nitrogen of the muck to decay. 



Cover Crops For Muck. 



Question: How about cover crops for muck soils? 

 Professor Van Slyke : They are very desirable to a cer- 



