FERTILIZERS FOR VEGETABLES 



239 



Raw Rock For Muck. 



Mr. M. B. McCargo : Do you advise using raw rock phos- 

 phate on muck? 



Professor Van Slyke: Yes. On the acid mucks, raw 

 rock phosphate has been found generally to give excellent re- 

 sults. While I would not depend upon that wholly without 

 knowing the conditions of the soil, I would use acid phos- 

 phate, but I would put on some raw rock phosphate too. 



Mr. McCargo : How long before it is available? 



Professor Van Slyke: It ought to show some avail- 

 ability the first season. In Illinois where they have heavy, 

 black, acid soils, they are using the rock phosphate very satis- 

 factorily untreated. They simply put on a thousand pounds 

 an acre once in four or five years. That appears to be suffi- 

 cient for farm crops or other grains. It seems to be abso- 

 lutely useless unless there is plenty of organic matter. As 

 vegetable matters decay, additional acid is formed. That is 

 very desirable. A good many of the muck soils are already 

 acid, and they have not very much plant food in them to dis- 

 solve. One characteristic of muck soils is deficiency in 

 potash and phosphoric acid. They do as a rule contain lots 

 of nitrogen, but it is not in a readily available form. 



Question: Does it make any difference about the acid 

 when a green crop is plowed under? 



Professor Van Slyke : I do not know as it makes much 

 difference providing the soil is not on the verge of acidity. 



Lime On Muck. 



Question: What do you recommend as to the use of lime 

 on muck soils? 



Professor Van Slyke : It is generally desirable, but it is 

 important to work it in pretty deep. If you work in only the 

 first two or three inches, you will find that the soil burns out, 

 as it were, and does not hold moisture in that upper layer, 

 so it is desirable, if you lime the soil, to work it in four or five 

 or six inches. 



