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United States Department of Agriculture

Agricultural Research Service

Title: Ion Partitioning among Soil and Plant Components under Drip, Furrow, and Sprinkler Irrigation Regimes: Field and Modeling Assessments

Authors
item Wang, Dong - U OF MINN, ST PAUL
item Shannon, Michael
item Grieve, Catherine
item Shouse, Peter
item Suarez, Donald
item Suarez, Donald

Submitted to: Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2002
Publication Date: N/A
Repository URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P1832.pdf

Interpretive Summary: In irrigated agriculture, leaching is usually required to remove excessive amounts of salts from accumulating in the soil to levels that inhibit plant growth. This study was conducted to examine salts between soil and soybean plants under different irrigation regimes. In drip and sprinkler treatments, the irrigation water was salinized with salts to simulate saline drainage water. In the furrow irrigation treatment, the soil was salinized, prior to planting. A total of 756 soil and 864 plant samples were collected and analyzed. Results indicated that about 20% of the applied salts were recovered in harvested soybean in all treatments. Plant uptake of salts were less than 0.5% in the drip and furrow, and about 2% in the sprinkler irrigation treatment. Significant increases in soil salinity were found in the sprinkler plot that received the highest cumulative amount of salts. Simulated chloride salt distributions in the soil were comparable to the measurements. Compared to the total seasonal salt input, mass balances between 65 and 108% were obtained. Most salt inputs accumulate in the soil, and need to be removed periodically to prevent soil salinization.

Technical Abstract: Soil and water resources can be severely degraded by salinity when total salt input exceeds output in irrigated agriculture. This study was conducted to examine partitioning of Ca2+, Na+, and Cl- between soil and soybean plants under different irrigation regimes using both field and modeling assessments. In drip and sprinkler treatments, the irrigation water was salinized with NaCl and CaCl2 salts to simulate a Cl- and Na+ dominant saline drainage water. In the furrow irrigation treatment, the soil was salinized, prior to planting, with NaCl and CaCl2 salts to simulate a Cl- and Na+ dominant saline soil. A total of 756 soil and 864 plant samples were collected and analyzed for the salt ions to obtain ion partitioning and mass balance assessments. Modeling of salt ion uptake by plants and distribution in the soil profile was carried out with a two-dimensional solute transport model for the three irrigation regimes. Results indicated that about 20% of the applied Ca2+ was recovered in harvested soybean biomass in all treatments. Plant uptake of either Na+ or Cl- was less than 0.5% in the drip and furrow, and about 2% in the sprinkler irrigation treatment. Significant increases in soil salinity were found in the sprinkler plot that received the highest cumulative amount of salts. Simulated ion distributions in the soil were comparable to the measurements. Compared to the total seasonal salt input, mass balances between 65 and 108% were obtained. Most salt inputs accumulate in the soil, and need to be removed periodically to prevent soil salinization.

Last Modified: 11/27/2014
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