Publicação
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
| Resumo: | 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. |
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| Autores principais: | Figueiredo, N. |
| Outros Autores: | Carranca, C.; Goufo, P.; Pereira, J.; Trindade, H.; Coutinho, J. |
| Assunto: | Clay soil Controlled environment Non-exchangeable NH4 + Open-field Soil depth |
| Ano: | 2015 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade Politécnica de Viseu |
| Idioma: | inglês |
| Origem: | Repositório Científico da Universidade Politécnica de Viseu |
| Resumo: | 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. |
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