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Effects of Initial Soil Moisture, Clod Size, and Clay Content on Ammonia Volatilization after Subsurface Band Application of Urea
Author(s) -
Pelster D. E.,
Watt Devon,
Strachan Ian B.,
Rochette P.,
Bertrand N.,
Chantigny M. H.
Publication year - 2019
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2018.09.0344
Subject(s) - volatilisation , water content , ammonia volatilization from urea , environmental science , urea , moisture , ammonia , environmental chemistry , clay soil , soil science , chemistry , soil water , geology , geotechnical engineering , organic chemistry
Ammonia losses from broadcast urea vary based on soil physical and chemical properties; however, less is known about how soil properties affect NH 3 losses after subsurface banding of urea. Therefore, three field trials were established to determine how initial soil moisture, clod size, and clay content affect NH 3 volatilization from subsurface‐banded (0.025‐m depth) urea using wind tunnels. The first study measured volatilization after banding in a loamy mixed frigid Typic Humaquept at 50, 100, 150, 200, or 250 g kg −1 gravimetric water content (WC). Study 2 measured volatilization from the same soil after covering the bands with soil clods that ranged from <2 to >24 mm in diameter, whereas Study 3 measured volatilization from transplanted, acidic soils with clay contents ranging from 5 to 57%. Cumulative 17‐d NH 3 losses for study one ranged from 8.3 to 20.8% of applied N, with the soil wetted to 200 g kg −1 WC experiencing the greatest losses. For Study 2, cumulative NH 3 volatilization losses ranged from 10.8 to 20.8% of applied N, with the greatest losses from the largest clod sizes. For Study 3, NH 3 losses ranged from 2.5 to 51.7% of applied N, with the NH 3 losses correlated to the maximum pH measured in the band ( P < 0.001), and to the soil cation exchange capacity ( P = 0.054), titratable acidity ( P = 0.072), and clay content ( P = 0.100). However, the soil with high silt, not sand, content had the highest volatilization losses, suggesting that high silt soils may have the greatest potential for NH 3 volatilization. Core Ideas Greater NH 3 losses from soils at 200 g kg −1 water content than at ≤150 g kg −1 . Covering the urea band with clods <6 mm reduced NH 3 losses. Soil NH 3 losses correlated closely to the maximum pH reached in the band and soil CEC. The highest NH 3 losses were from soils with low clay and high silt content. Previous Canadian studies on NH 3 loss from banded urea may overestimate losses.