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Substitution of Ammonium and Potassium for Added Calcium in Reduction of Ammonia Loss from Surface‐applied Urea
Author(s) -
Fenn L. B.,
Matocha J. E.,
Wu E.
Publication year - 1982
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/sssaj1982.03615995004600040021x
Subject(s) - chemistry , urea , potassium , ammonia , ammonia volatilization from urea , fertilizer , inorganic chemistry , ammonium , nitrate , nitrogen , potassium nitrate , cation exchange capacity , soil water , calcium nitrate , chloride , ammonium nitrate , calcium , organic chemistry , soil science , environmental science
Ammonia (NH 3 ) volatilization loss from surface application of urea must be reduced if urea is to gain further acceptance for use in pastures and on other non‐ or low‐tillage systems which do not permit soil incorporation. The method used to reduce NH 3 loss should not increase costs of the N fertilizer significantly. Preferably, the material used should itself be a fertilizer nutrient. The nitrate salts of the monovalent cations NH + 4 , K + , and Na + were tested as substitutes for chloride or nitrate salts of Ca 2+ to depress NH 3 losses when mixed with surface‐applied urea. Ammonia losses were measured from soils with different cation exchange capacities (CEC) in the laboratory, with residual N quantified by growing sudangrass on the variously treated soils under greenhouse conditions. Laboratory and/or greenhouse data indicate that NH 3 loss from surface‐applied urea was most effectively reduced by Ca salts. Substitution of K, Na, and NH 4 salts for Ca salts was increasingly effective as soil CEC increased. Monovalent salts were effective in reducing NH 3 losses if the soil had exchangeable Ca 2+ + Mg 2+ . In sand, however, monovalent salts did not reduce NH 3 losses. The order of effectiveness on nonsandy soils was Na + = K + > NH + 4 in reducing NH 3 loss. Potassium as KNO 3 or KCl can be used effectively to partially replace (Ca + Mg) nitrate or chloride salts with urea to reduce NH 3 losses. Ammonium nitrate was ineffective in reducing NH 3 losses except where high N application rates were used or where little or no soil CEC existed. The efficacy of NH 4 NO 3 seemed to be due to its acidic nature more than displacement of exchangeable Ca 2+ + Mg 2+ .