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Nitrogen Dynamics in Irrigated Corn: Soil‐Plant Nitrogen and Atmospheric Ammonia Transport
Author(s) -
Harper Lowry A.,
Sharpe Ronald R.
Publication year - 1995
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1995.00021962008700040011x
Subject(s) - environmental science , agronomy , growing season , atmosphere (unit) , nitrogen , flux (metallurgy) , cropping system , nitrous oxide , crop , chemistry , biology , meteorology , physics , organic chemistry
Ammonia transport in cropping systems can affect atmospheric pollution, soil‐plant N relationships, and crop N‐use efficiency. The purpose of this study was to evaluate the N dynamics of a corn ( Zea mays L., Pioneer hybrid 3379) cropping system and determine the effect of NH 3 transport and crop NH 3 compensation point on N relations in the crop. Soil and plant N measurements were made during the growing season along with plant‐atmosphere NH 3 transport using flux‐gradient micrometeorological techniques. The crop generally emitted NH 3 throughout the season when the atmospheric NH 3 concentrations were near background levels. During periods of high atmospheric NH 3 concentrations, the crop absorbed significant amounts of NH 3 from the atmosphere. Net seasonal NH 3 transport was determined to be a small loss, based on the number of measurement periods throughout the growing season; however, N isotope studies in a nearby field estimated significant NH 3 losses. Nitrogen isotope studies cannot account for the substitution of 14 NH 3 absorbed from the atmosphere for volatilized 15 NH 3 . These results indicate that care must be taken when using N isotopes to evaluate N losses from cropping systems when plants are actively growing. Nitrous oxide flux was measured late in the cropping season, but showed small denitrification losses during the measurement period. The crop NH 3 compensation point varied during the time of day and with respect to soil‐plant‐atmosphere influence. Net NH 3 transport accounted for little of the N lost from this cropping system.