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Advisor(s)
Abstract(s)
Data on the movements of available N and non-exchangeable NH4
+ in the soil are of crucial importance in
designing an efficient plant N nutrition management scheme in paddy rice fields. To investigate the
processes affecting the dynamics of N and pH under Mediterranean conditions, rice (Oryza sativa L. cv.
Ariete) was cultivated in 2011 and 2012 in Salvaterra de Magos (central Portugal) under the following
climate scenarios: (i) ambienttemperature and ambient [CO2] in the open-field, (ii) elevated temperature
(+3 C) and ambient [CO2] in open-top chambers, and (iii) elevated temperature (+3 C) and elevated
[CO2] (+175mmol mol1
) in open-top chambers. Plants were grown under an intermittent flooding
regime. Soil and water samples were taken at eight different stages of plant growth, including before and
after N basal and topdressing. Our study indicated that the processes underlying N changes in response to
the timing of N fertilization were different depending on the N form. After basal dressing under aerobic
conditions, both available and non-exchangeable NH4
+ contents were increased. Following the
topdressing under flooded conditions, the available content of soil N increased, whereas the
non-exchangeable NH4
+ content decreased. A negative relationship was found between soil pH and
NH4
+ “fixation” when roots were active, and vice-versa. Elevated temperature alone or in combination
with elevated [CO2] had no effect on the total available N content in the soil and floodwater. Under
elevated temperature, however, the non-exchangeable NH4
+ content was significantly reduced (11%),
with the same magnitude of change (10%) observed under co-elevation of temperature and [CO2]. These
results suggested that non-exchangeable NH4
+ in paddy fields might be insensitive to [CO2] elevation
under Mediterranean conditions, while reductions observed under co-elevation of [CO2] and
temperature might be associated with temperature alone. This information could be used to alter
rice management practices and to adjust N application under climate change.
Description
Keywords
Clay soil Controlled environment Non-exchangeable NH4 + Open-field Soil depth
Pedagogical Context
Citation
Figueiredo N., Carranca C., Goufo P., Pereira J., Trindade H., Coutinho, J. (2015). Impact of agricultural practices, elevated temperature and atmospheric carbon dioxide concentration on nitrogen and pH dynamics in soil and floodwater during the seasonal rice growth in Portugal. Soil and Tillage Research 145: 198-207.
Publisher
Elsevier