Published October 1, 2021 | Version 1
Journal article Open

The influence of fertilizers on the behavior of fluoride fractions in the alkaline soil

  • 1. The Nelson Mandela African Institute of Science and Technology, School of Material, Energy, Water and Environmental Sciences, P.O. Box 447, Nambala, Arusha, Tanzania
  • 2. Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB. UK

Description

It has been established that fluoride bioavailability in the soil is defined by the form which it exists rather than the amount of total fluoride. In the soil, fluoride exist in different fractions such as water soluble (Ws-F), Exchangeable (Ex-F), bound to iron/manganese (Fe/Mn-F), organic matter bound (Or-F), and the residual (Res-F). All of these fractions are bioavailable however to different extents in an order Ws-F>Ex-F>Fe/Mn-F>Or-F>Res-F. Agricultural practices such as fertilizer application alters the behavior of these fractions which further affects fluoride bioavailability in the soil. This study investigated the influence of the three commonly used fertilizers (Di-ammonium Phosphate (DAP), Urea, and cow-manure) on the bioavailability of soil fluoride in an alkaline soil. The soil was mixed with either one of the fertilizers then incubated for a period of five months. All three fertilizers increased the amount of Ws-F by 7.8 ± 0.6, 4.1 ± 0.2, 9.6 ± 1.1 mg/kg and Fe/Mn-F by 2.24 ± 0.3, 0.44 ± 0.2, and 2.1 ± 0.2 mg/kg, for DAP, Urea, and manure amendments, respectively, but had no impact on the amount of Or-F. All three fertilizers were observed to enhance the bioavailability of fluoride in the soil by increasing the amount of Ws-F. The fertilizers could have increased the bioavailability of fluoride in the soil directly or indirectly through alteration of pH and the soil elemental composition. The three fertilizers might not be suitable for use in fluoride contaminated alkaline soils as they accelerate fluoride release and hence bioavailability in the soil.

Notes

Other funding acknowledgements: Partnership for Applied Skills in Sciences, Engineering and Technology-Regional Scholarship Innovation Fund (PASET-RSIF)

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The influence of fertilizer on the behavior of fluoride fractions in the alkaline soil.pdf

Additional details

Funding

EWA - BELT – Linking East and West African farming systems experience into a BELT of sustainable intensification 862848
European Commission