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Agriculture

Agricultural Managed Aquifer Recharge May Impact Nitrogen Leaching in Groundwater

Strategic Insights

— 2 min read

Researchers at the University of California, Davis, have discovered that agricultural managed aquifer recharge (Ag-MAR) practices may affect the leaching of legacy nitrate from fertilizer applications to groundwater or nitrogen transformations such as mineralization or denitrification. The study used the DSSAT model to simulate the impact of different Ag-MAR practices on the growing season water and nitrogen budgets. Results showed that scheduling Ag-MAR closer to the growing season benefits the root zone water content and crop yield, while reducing growing season irrigation demand by 10%. Continuous flooding for longer periods of time, well in advance of the growing season, provides the greatest recharge potential with no adverse effects on the growing season nitrogen budget.

Key Takeaways:

  • Agricultural managed aquifer recharge (Ag-MAR) may impact the leaching of legacy nitrate from fertilizer applications to groundwater or nitrogen transformations such as mineralization or denitrification.
  • The timing and intermittency of flooding in Ag-MAR practices directly impact the amount of nitrate leached, and the residual amount of nitrate available at the beginning of the growing season.
  • Scheduling Ag-MAR closer to the growing season benefits the root zone water content and crop yield, reducing growing season irrigation demand by 10%.
  • Continuous flooding for longer periods of time, well in advance of the growing season, provides the greatest recharge potential with no adverse effects on the growing season nitrogen budget.
  • The study used the DSSAT model to simulate the impact of different Ag-MAR practices on the growing season water and nitrogen budgets.
  • Results showed that early and continuous Ag-MAR promotes the mineralization of new nitrate, which offsets nitrate leaching and allows for water and nitrogen fertilizer savings during the growing season.
  • The research has been peer-reviewed and published in the journal Agricultural Water Management.

Statistics:

  • 317: The issue number of the journal Agricultural Water Management where the research is published.
  • 10%: The reduction in growing season irrigation demand by scheduling Ag-MAR closer to the growing season.
  • 2 months: The time period in advance of the growing season where continuous flooding provides the greatest recharge potential.
  • January-April: The timing of flooding in Ag-MAR practices that directly impact the amount of nitrate leached.

Sources:

  • Modeling the Impact of Agricultural Managed Aquifer Recharge (Ag-mar) On Soil Water and Nitrogen Dynamics of the Growing Season. Agricultural Water Management, 2025; 317.
  • University of California Davis, Department of Land Air and Water Resources.
  • Wenyi Cui, Tiantian Zhou, Cristina Prieto Garcia, Isaya Kisekka, and Elad Levintal.

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