Premium
Relative Effect of Different Superphosphates on the Preservation of Nitrogen in Cow Manure
Author(s) -
Midgley A. R.
Publication year - 1937
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1937.03615995000100000052x
Subject(s) - citation , manure , nitrogen , library science , mathematics , computer science , agronomy , chemistry , biology , organic chemistry
Many dairymen use superphosphate in their stables to balance and conserve their farm manure supplies. Superphosphates containing more than 16$ available phosphoric acid are now available, and the question arises whether they are equal to, or better than, the 16$ grades for this purpose. The Vermont Station has been at work on this problem for some time. Superphosphates containing 16$, 20$, and 40$ of available phosphoric -acid were obtained. These differ decidedly in their calcium sulphate (gypsum) contents. The 20$ granulated goods contain more than any of the others; being dryer, much of the hygroscopic water, as well as the water of crystallization, being removed in the granulation process. Since the run-ofpile goods now made may contain 20$ P20S, sand or lime is often used as a filler to make it grade 16$, which would account for its somewhat lower gypsum content. The several grades contain approximately: 20$ granular 60$, 20$ pulverized 58$, 16$ pulverized 54$, 40$ pulverized 3-4$ gypsum. One should recognize the role which calcium sulphate plays in the preservation of manurial nitrogen in order to understand the differences between the different grades. Neither calcium sulphate nor mono-calcium phosphate, alone greatly reduces manurial nitrogen losses by volatilization, especially if the mixture is allowed to dry. However, when the two are intermingled they become much more effective, because of their reciprocal chemical reactions in the presence of ammonia in the manure, which can be best understood by considering the following reactions: