EGU21-8780
https://doi.org/10.5194/egusphere-egu21-8780
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Reducing leaching using the threshold nitrate root-uptake phenomena

Daniel Kurtzman1, Beeri Kanner2, Yehuda Levy3, Ido Nitsan1, and Asher Bar-Tal1
Daniel Kurtzman et al.
  • 1Institute of Soil, Water and Environmental Sciences, the Volcani Center, Agricultural Research Organization, POB 15159, Rishon LeZion 750510, Israel. (daniel@volcani.agri.gov.il)
  • 2Department of Soil and Water Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Israel
  • 3Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel

Reducing nitrate leaching from agricultural land to aquifers is a high priority concern for more than a half a century. Theory and observations of a threshold concentration of nitrate in the root-zone (Cmax), from which the leachate concentration increases at higher rates with increasing root-zone nitrate concentration, are presented. Cmax is derived both by direct results from container experiments with varying nitrogen (N) fertigation, and as calibration parameter in N-transport models beneath commercial agricultural plots. For five different crops, Cmax ranged between 20-45 mg/l of NO3-N derived from experiments and models. However, for lettuce, which was irrigated with a large leaching fraction, a Cmax could not be defined. For the crops irrigated and fertilized in the warm/dry season (corn and citrus) experiments show a dramatic change in leachate concentrations and simulations reveal a wide range of sensitivity of leachate NO3-N concentration to Cmax. Annual crops that are irrigated and fertilized in the cool/wet season (e.g. potato in Mediterranean climate) showed a distinct Cmax yet less dramatic than the summer-irrigated crops in the container experiment, and smaller impact of Cmax in models. Simulations showed that for summer-irrigated crops maintaining fertigation at C<Cmax has a significant effect on deep leachate concentrations, whereas for the winter annual crops the simulations revealed no threshold. It is suggested that for summer-irrigated crops fertigation below Cmax robustly serves the co-sustainability of intensive agriculture and aquifer water quality, for the winter crops it is suggested but benefits are not robust. For short season, small root-system crops (lettuce) efforts should be made to detach the crop from the soil.

How to cite: Kurtzman, D., Kanner, B., Levy, Y., Nitsan, I., and Bar-Tal, A.: Reducing leaching using the threshold nitrate root-uptake phenomena, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8780, https://doi.org/10.5194/egusphere-egu21-8780, 2021.

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