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Measuring Phosphorus Release in Laboratory Microcosms for Water Quality Assessment
Published on: July 22, 2019
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Mechanisms Responsible for Soil Phosphorus Availability Differences between Sprinkler and Furrow Irrigation.
Journal of Environmental Quality
|October 8, 2019
Summary
Long-term furrow irrigation increases soil phosphorus (P) availability in aridic soils compared to modern sprinkler systems. This shift is linked to altered P forms and calcium-associated P dynamics under flooded conditions.
Area of Science:
- Soil Science
- Agricultural Science
- Environmental Science
Background:
- Human-induced soil erosion and phosphorus (P) loss have historical roots.
- Converting from furrow to sprinkler irrigation can reduce erosion and off-site P transport.
- Irrigation method changes may impact soil nutrient dynamics, particularly P.
Purpose of the Study:
- To investigate and compare soil P dynamics between long-term furrow-irrigated and recently installed sprinkler-irrigated fields.
- To understand how different irrigation practices influence the forms and availability of soil P in Aridisols.
- To identify the mechanisms behind observed differences in plant-available P.
Main Methods:
- Analysis of Olsen-extractable P (plant-available P) in soil samples from paired fields.
- Utilized modified Hedley extraction to characterize inorganic P pools.
- Employed Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy to identify P-mineral associations.
Main Results:
- Furrow-irrigated soils exhibited significantly higher Olsen-extractable P (38 mg kg) than sprinkler-irrigated soils (20 mg kg).
- Furrow-irrigated soils showed greater concentrations in soluble+Al-bound+Fe-bound, occluded, and amorphous Fe-bound P pools.
- XANES indicated more apatite-like or octacalcium phosphate-like P in furrow-irrigated soils, and greater calcite-bound P in sprinkler-irrigated soils.
Conclusions:
- Long-term furrow irrigation, even in aridic calcareous soils, leads to higher plant-available P concentrations.
- Altered iron (Fe) redox chemistry and calcium (Ca)-associated P dynamics in flooded furrow conditions likely contribute to increased P availability.
- Sprinkler irrigation may lead to a slower transformation of P pools, with a greater proportion bound to calcite.
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