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Evaluation of Urea‐Urea Phosphate as a Nitrogen Source for No‐tillage Production
Author(s) -
Urban W. J.,
Hargrove W. L.,
Bock B.R.,
Raunikar R.A.
Publication year - 1987
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/sssaj1987.03615995005100010049x
Subject(s) - urea , urease , diammonium phosphate , chemistry , ammonium nitrate , ammonia volatilization from urea , soil water , phosphoric acid , agronomy , nitrogen , tillage , ammonium , fertilizer , nitrate , environmental science , soil science , organic chemistry , biology
Urea‐urea phosphate (UUP), a combination of urea and phosphoric acid, has properties which reduce the potential for NH 3 volatilization but has not been evaluated extensively under field conditions. The objective of this study was to evaluate UUP (34‐17‐0) under laboratory and field conditions. All experiments were conducted on acid sandy soils typical of the predominant Ultisols found in the southeastern USA. A forced‐draft technique was used to make direct measurements of NH 3 losses in a growth chamber and also in the field. In addition, UUP and six other N sources were compared for no‐till grain sorghum ( Sorghum bicolor L. Moench) production. Direct measurement of NH 3 losses in the growth chamber resulted in small losses from UUP on both mulched and bare soils, while NH 3 losses from urea ranged from 15 to 32% of the applied N on a bare soil and 68 to 82% on a mulched soil. Direct field measurement of NH 3 losses from urea, UUP, and ammonium nitrate applied at 200 kg N/ha were 19, 5, and 2% of the applied N, respectively. In the field plot studies, UUP compared favorably with ammonium nitrate and calcium nitrate with respect to crop response. The mechanism of NH 3 loss prevention appears to be pH buffering by the phosphoric acid component of UUP. It is concluded that UUP is an effective N source for surface application to noncalcareous soils under no‐tillage management.