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Biodiversity-safeguarding threshold for urea-fertilizer application on paddy fields: Protozoa-based toxicity tests. | LitMetric

Biodiversity-safeguarding threshold for urea-fertilizer application on paddy fields: Protozoa-based toxicity tests.

J Environ Manage

Laboratory of Protozoa, College of Life Science and Technology, Harbin Normal University, Harbin, 150025, China; Key Laboratory of Biodiversity of Aquatic Organisms, Harbin Normal University, Harbin, 150025, China. Electronic address:

Published: November 2024

AI Article Synopsis

  • - Urea is commonly used to boost crop yields, but its overuse poses ecological risks and threatens sustainable agriculture and biodiversity in paddy fields.
  • - This study identifies Blepharisma sp. as the most sensitive organism to urea, making it an effective indicator for determining safe urea application thresholds in rice fields.
  • - The short-term safety threshold for urea application in paddy fields is set at 87.7 mg/L (43.85 kg/ha), while the long-term threshold is 5.02 mg/L, establishing guidelines for reducing urea use to protect biodiversity.

Article Abstract

Urea is a widely applied fertilizer to enhance crop yields. Ecological risks associated with the excessive application of urea fertilizer threaten the paddy fields' sustainable agriculture and biodiversity preservation. There are no practical thresholds based on proven data on microbial communities. Protozoa are nitrogen-sensitive organisms. For the first time, this study conducted acute and chronic urea toxicity tests on eight species of organisms. The results indicate that Blepharisma sp. is the most sensitive species to urea exposure and is a suitable indicator for determining the safe threshold of urea. This study estimated the predicted no-effect concentration using species sensitivity distribution curves. Subsequently, it established the threshold for urea application in rice fields based on the fields' area and the surface water's height. The short-term safety threshold for urea in the studied paddy field with black soil is 87.7 mg/L, equivalent to 43.85 kg of urea per hectare for a single nitrogen fertilizer application. The long-term safety threshold is 5.02 mg/L, representing the concentration for re-applicating urea. The biodiversity-safeguarding application threshold provides the basis for developing a urea fertilizer reduction protocol to safeguard the paddy fields' biodiversity.

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Source
http://dx.doi.org/10.1016/j.jenvman.2024.122836DOI Listing

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