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High Yielding Cotton Produced without Excessive Nitrous Oxide Emissions
Author(s) -
Macdonald Bennett C. T.,
Rochester Ian J.,
Nadelko Anthony
Publication year - 2015
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/agronj14.0369
Subject(s) - fertilizer , nitrous oxide , agronomy , rotation system , crop rotation , environmental science , urea , nitrogen , gossypium hirsutum , vicia faba , growing season , crop , zoology , chemistry , biology , organic chemistry
Excessive N fertilizer use leads to enhanced nitrous oxide (N 2 O) emissions from cotton ( Gossypium hirsutum L.) production systems. The objective of the study was to quantify nitrous oxide emissions from the ridges within a furrow‐irrigated field during the growth of a cotton crop that had been fertilized with urea at 0, 120, 200, or 320 kg N ha −1 . No measurements were taken from the furrows; we assumed similar N 2 O emissions from the furrows in this system. The N 2 O emissions increased exponentially with N fertilizer rate. Over the cotton‐growing season, N 2 O emissions totalled 0.51, 0.95, 0.78, and 10.62 kg N 2 O‐N ha −1 , for the four respective N fertilizer rates. The cotton phase of the cotton–faba bean ( Vicia faba L.)–fallow rotation was the main contributor to the total N 2 O emission. Over this 2‐yr rotation, emissions totalled 1.23, 1.65, 1.44, and 11.48 kg N 2 O‐N ha −1 . However, <0.35% of the N fertilizer applied was emitted as N 2 O for the complete rotation where the economic optimal N fertilizer rate for the cotton crop was not exceeded. More than 3.5% of the N fertilizer was emitted as N 2 O where 320 kg N ha −1 was applied, which was estimated to represent about 11 kg N ha −1 . These data indicate that supra‐optimal N fertilizer applications increase the net emissions of N 2 O from the ridges in high‐yielding furrow‐irrigated cropping systems. The N 2 O emissions could be decreased further by reducing or eliminating the time in fallow.