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Ammonia Volatilization from Broadcast Urea and Alternative Dry Nitrogen Fertilizers
Author(s) -
Del Moro Sarah K.,
Sullivan Dan M.,
Horneck Donald A.
Publication year - 2017
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/sssaj2017.06.0181
Subject(s) - urea , chemistry , ammonia volatilization from urea , urease , ammonium sulfate , ammonia , fertilizer , nitrogen , ammonium , inorganic chemistry , zoology , environmental chemistry , biochemistry , organic chemistry , biology
Core Ideas Volatile NH 3 loss in the field was quantified via the modified passive flux method. Urease inhibitor (NBPT) or S‐coated urea reduced N loss by 39 to 53% versus urea. Urea plus ammonium sulfate (Urea‐AS) reduced N loss by 19 to 28% versus urea. A companion laboratory trial found the same relative efficacy among fertilizers. Substantial ammonia (NH 3 ) loss can occur when urea is broadcast without incorporation. Choosing an alternate fertilizer (instead of urea) is one option when incorporation of urea by tillage or sprinkler irrigation is not feasible. This research evaluated alternative N fertilizer products (vs. urea) using the modified passive flux method. Fertilizers were broadcast (168 kg N ha –1 ) on an Irrigon fine sandy loam soil (mesic Xeric Haplocambid), and not incorporated. Light showers (7 mm in 14 d after application) triggered NH 3 loss. After 34 d, ammonia‐N loss was 14 to 17% of N applied as ammonium sulfate (AS) or ASN (fused granule of ammonium sulfate and ammonium nitrate), 22% as S‐coated urea (SCU), 28% as urea + urease inhibitor NBPT [N‐(n‐butyl) thiophosphoric triamide], and 33 to 37% as blended or fused urea‐AS fertilizers (79:21 urea/ammonium sulfate, w/w) vs. 46% as urea. A companion 44‐d laboratory study (16°C) demonstrated a similar ranking of fertilizer efficacy. We conclude that fusing AS with urea in a granule (instead of blending) did not reduce NH 3 loss. Partial substitution of AN for AS in a fused granule (ASN) did not provide additional benefit in reducing NH 3 loss vs. AS alone. Treated urea products (SCU and urea + NBPT) had greatest efficacy in reducing NH 3 loss during the first 10 d after application, with reduced efficacy thereafter, likely due to the degradation of the coating (SCU) or the urease inhibitor NBPT.