EGU22-4489, updated on 27 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Slow-release fertilizers from liquid digestate: amount and speciation of the N leached in a laboratory column experiment

Giacomo Ferretti1, Giulio Galamini2, Valeria Medoro2, Barbara Faccini2, and Massimo Coltorti2
Giacomo Ferretti et al.
  • 1University Of Ferrara, Department of Chemical, Pharmaceutical and Agricultural Sciences, Ferrara, Italy (
  • 2University of Ferrara, Department of Physics and Earth Science, Ferrara, Italy

The inefficient management of fertilizers is dramatically impairing the soil, water, and atmosphere quality. Efficient alternative methodologies for granting adequate N availability to crops while reducing the nutrient losses in the environment are urgently needed. In this work, we present a column leaching experiment in which the amount and speciation of the N lost by different slow-release fertilizers were investigated, in comparison to traditional fertilizers (urea and liquid digestate). The slow-release alternatives are produced by recovering N from liquid digestate and represented by NH4-enriched zeolite-rich tuff and struvite. Four treatments were tested consisting in sandy soil fertilized with urea, liquid digestate, NH4-enriched zeolite tuff and struvite. N amount and speciation was accounted in eight flushing events over 38 days (Total Kjeldahl N, Organic-N, NH4+-N, NO3--N, NO2--N).

Results showed that urea and liquid digestate fertilized columns lost the majority of N within the first 2 flushing events as organic N and NH4+-N, respectively. On the contrary, struvite and NH4-enriched zeolite fertilized columns lost homogeneously fewer N and with a more balanced speciation over the entire experiment length. The mass balance outlined that, native soil N was mined in urea and liquid digestate treatments while in the soil fertilized with slow-release alternatives a fraction of N from the fertilizers was still present. These two slow-release alternatives thus representing a way to recycle N from liquid digestate and to use it more efficiently, minimizing N losses.

How to cite: Ferretti, G., Galamini, G., Medoro, V., Faccini, B., and Coltorti, M.: Slow-release fertilizers from liquid digestate: amount and speciation of the N leached in a laboratory column experiment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4489,, 2022.