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Author Liang, X. Q. ♦ Harter, T. ♦ Porta, L. ♦ Van Kessel, C. ♦ Linquist, B. A.
Source World Health Organization (WHO)-Global Index Medicus
Content type Text
Publisher American Society of Agronomy
File Format HTM / HTML
Language English
Difficulty Level Medium
Subject Domain (in DDC) Technology ♦ Medicine & health ♦ Diseases ♦ Agriculture & related technologies ♦ Techniques, equipment & materials
Subject Keyword Discipline Environmental Health
Abstract Irrigated croplands can be a major source of nitrate-N (NO-N) in groundwater due to leaching. In California, where high NO-N levels have been found in some areas of the Central Valley aquifer, the contribution from rice systems has not been determined. Nitrate leaching from rice systems was evaluated from soil cores (0-2 m), from the fate of N fertilizer in replicated microplots, and from about 145 regional groundwater wells. Soil NO-N concentrations were ≤3.3 mg kg (usually <1 mg kg) below the root zone (below 33 cm depth). In pore-water samples, NO-N was observed only below the root zone during the first 2 wk after the onset of flooding in either the growing season or the winter fallow period and was always ≤8.4 mg L. Fertilizer N accounted for 0 to 11.8% of NO-N in pore-water samples below the root zone. One year after application, based on an analysis of soil core samples, on average 2.5% of fertilizer N was recovered as N below the root zone (33-100 cm), possibly due to leaching in permeable soils or via preferential flow through cracks in heavy clay soils. Based on a regional assessment, groundwater samples from wells that are located in proximity to rice fields all had measured median NO-N and NO-N levels below 1 mg L. These results indicate that NO-N leaching from the majority of California rice systems poses little risk to groundwater under current crop management practices.
ISSN 00472425
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Reading ♦ Research ♦ Self Learning
Interactivity Type Expositive
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2014-05-01
Publisher Place United States
e-ISSN 15372537
Journal Journal of Environment Quality
Volume Number 43
Issue Number 3

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Source: WHO-Global Index Medicus