Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in Rice
Arsenic availability to rice is tied to biogeochemical cycling of Fe and Mn in rice soils. Two strategies to minimize As uptake by rice—increasing Si and decreasing water—affect soil Fe and Mn pools. We synthesized data from several soil-based experiments with four rice cultivars...
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MDPI AG
2019-08-01
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| Series: | Soil Systems |
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| Online Access: | https://www.mdpi.com/2571-8789/3/3/58 |
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| author | Angelia L. Seyfferth Matt Limmer Weida Wu |
| author_facet | Angelia L. Seyfferth Matt Limmer Weida Wu |
| author_sort | Angelia L. Seyfferth |
| collection | DOAJ |
| description | Arsenic availability to rice is tied to biogeochemical cycling of Fe and Mn in rice soils. Two strategies to minimize As uptake by rice—increasing Si and decreasing water—affect soil Fe and Mn pools. We synthesized data from several soil-based experiments with four rice cultivars across pot and field trials with manipulations of Si, water, or both. Increasing Si alters the mineral composition of Fe plaque more than decreasing water, with the former promoting relatively more ferrihydrite and less lepidocrocite. Nonflooded conditions decrease lepidocrocite but slightly increase goethite compared to flooded rice. Plaque As, which was a mixture of arsenite (15−40%) and arsenate (60−85%), was correlated positively with ferrihydrite and negatively with lepidocrocite and goethite. Plaque As was also positively correlated with F1 and F2 soil As, and F2 was correlated positively with porewater As, total grain As, and grain organic As (oAs). Grain inorganic As (iAs) was negatively correlated with oxalate-extractable Fe and Mn. Our data and multiple linear regression models suggest that under flooded conditions iAs is released by poorly crystalline Fe oxides to porewater mainly as iAs(III), which can either be taken up by the plant, adsorbed to Fe plaque, oxidized to iAs(V) or methylated to oAs. Increasing Si can promote more desorption of iAs(III) and promote more poorly-ordered phases in plaque and in bulk soil. The ultimate effectiveness of a Si amendment to decrease As uptake by rice depends upon it being able to increase exogenous Si relative to As in porewater after competitive adsorption/desorption processes. Our data further suggest that poorly crystalline Fe and Mn soil pools can retain inorganic As and decrease plant uptake, but these pools in bulk soil and plaque control grain organic As. |
| first_indexed | 2024-04-13T01:53:18Z |
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| id | doaj.art-d45a737083d04a1a8f147b79dd850665 |
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| language | English |
| last_indexed | 2024-04-13T01:53:18Z |
| publishDate | 2019-08-01 |
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| series | Soil Systems |
| spelling | doaj.art-d45a737083d04a1a8f147b79dd8506652022-12-22T03:07:50ZengMDPI AGSoil Systems2571-87892019-08-01335810.3390/soilsystems3030058soilsystems3030058Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in RiceAngelia L. Seyfferth0Matt Limmer1Weida Wu2Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, USADepartment of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, USADepartment of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, USAArsenic availability to rice is tied to biogeochemical cycling of Fe and Mn in rice soils. Two strategies to minimize As uptake by rice—increasing Si and decreasing water—affect soil Fe and Mn pools. We synthesized data from several soil-based experiments with four rice cultivars across pot and field trials with manipulations of Si, water, or both. Increasing Si alters the mineral composition of Fe plaque more than decreasing water, with the former promoting relatively more ferrihydrite and less lepidocrocite. Nonflooded conditions decrease lepidocrocite but slightly increase goethite compared to flooded rice. Plaque As, which was a mixture of arsenite (15−40%) and arsenate (60−85%), was correlated positively with ferrihydrite and negatively with lepidocrocite and goethite. Plaque As was also positively correlated with F1 and F2 soil As, and F2 was correlated positively with porewater As, total grain As, and grain organic As (oAs). Grain inorganic As (iAs) was negatively correlated with oxalate-extractable Fe and Mn. Our data and multiple linear regression models suggest that under flooded conditions iAs is released by poorly crystalline Fe oxides to porewater mainly as iAs(III), which can either be taken up by the plant, adsorbed to Fe plaque, oxidized to iAs(V) or methylated to oAs. Increasing Si can promote more desorption of iAs(III) and promote more poorly-ordered phases in plaque and in bulk soil. The ultimate effectiveness of a Si amendment to decrease As uptake by rice depends upon it being able to increase exogenous Si relative to As in porewater after competitive adsorption/desorption processes. Our data further suggest that poorly crystalline Fe and Mn soil pools can retain inorganic As and decrease plant uptake, but these pools in bulk soil and plaque control grain organic As.https://www.mdpi.com/2571-8789/3/3/58riceFe plaquearsenicsiliconwater management |
| spellingShingle | Angelia L. Seyfferth Matt Limmer Weida Wu Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in Rice Soil Systems rice Fe plaque arsenic silicon water management |
| title | Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in Rice |
| title_full | Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in Rice |
| title_fullStr | Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in Rice |
| title_full_unstemmed | Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in Rice |
| title_short | Si and Water Management Drives Changes in Fe and Mn Pools that Affect As Cycling and Uptake in Rice |
| title_sort | si and water management drives changes in fe and mn pools that affect as cycling and uptake in rice |
| topic | rice Fe plaque arsenic silicon water management |
| url | https://www.mdpi.com/2571-8789/3/3/58 |
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