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. 2025 Jul 25;18(15):3492.
doi: 10.3390/ma18153492.

A New High-Efficiency Fertilization System from Waste Materials for Soil Protection: Material Engineering, Chemical-Physical Characterization, Antibacterial and Agronomic Performances

Martina Napolitano  1 , Gianluca Malavasi  2 , Daniele Malferrari  2   3 , Giulio Galamini  2 , Michelina Catauro  4 , Veronica Viola  4 , Fabrizio Marani  2   5 , Luisa Barbieri  1   3
Affiliations

A New High-Efficiency Fertilization System from Waste Materials for Soil Protection: Material Engineering, Chemical-Physical Characterization, Antibacterial and Agronomic Performances

Martina Napolitano et al. Materials (Basel). .

Abstract

The development of slow-release fertilizers (SRFs) based on production residues is a promising strategy to improve nutrient use efficiency and promote circular economy practices in agriculture. In this study, a series of experimental formulations were designed and tested using pumice scraps, liquid and dried blood, and bone meal, aiming at producing sustainable and low-cost N-P-K SRFs. These were processed through mixing and granulation, both in the laboratory and on a semi-industrial scale. The formulations were evaluated through release tests in 2% citric acid solution simulating the acidic conditions of the rhizosphere, and in acetic acid to assess potential nutrient leaching under acid rain conditions. The results showed a progressive cumulative release of macronutrients (NPKs), ranging from approximately 8% at 24 h to 73% after 90 days for the most effective formulation (WBF6). Agronomic trials on lettuce confirmed the effectiveness of WBF6, resulting in significant biomass increases compared with both the untreated control and a conventional fertilizer. The use of livestock waste and minerals facilitated the development of a scalable product aligned with the principles of sustainable agriculture. The observed release behavior, combined with the simplicity of production, positions these formulations as a promising alternative to conventional slow-release fertilizers.

Keywords: circular economy; material engineering; matrix-based SRFs; organic matrix; slow-release fertilizers.

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Conflict of interest statement

Author Fabrizio Marani was employed by company LB Officine Meccaniche S.p.A., Via Pedemontana 166, 41042 Fiorano Modenese, Italy. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Schematic representation of the industrial wet granulation process. Granule formation occurs through successive mechanisms: nucleation, particle growth, layering and aggregation, followed by consolidation. Occasional breakage of agglomerates can also occur during the process.
Figure 2
Figure 2
Scanning Electron Microscope (SEM) images of WBF4, WBF5 and WBF6 granules.
Figure 3
Figure 3
Mass loss in bidistilled water (% w/w) measured for WBF4, WBF5 and WBF6 over a period of 28 days.
Figure 4
Figure 4
The kinetics of N (a), K2O (b) and P2O5 (c) release in citric acid (C) solution (2%) and acetic acid (A) solution (0.5 M) according to the TNC of NPK in the WBFs.
Figure 5
Figure 5
Monitoring of the % (w/w) mass loss in citric acid (C) and acetic acid (A) of WBF5 and WBF6.
Figure 6
Figure 6
pH of the filtrated solutions of WBF5 and WBF6 in extractant citric acid 2% (C) and acetic acid 0.5 M (A). The pH of blank solutions was also monitored.
Figure 7
Figure 7
Conductivity of the filtrated solutions of WBF5 and WBF6 in extractant citric acid 2% (C) and acetic acid 0.5 M (A). Conductivity of blank solutions was also monitored.
Figure 8
Figure 8
Biomass production: fresh index (FI) and dry index (DI) of WBF6 and WBF5. Data are means of five replicates, and the error bars represent the standard deviation. Multiple comparisons were performed with a Tukey–Kramer test. Symbols ** and *** indicate significance at p < 0.01 and p < 0.001, respectively.
Figure 9
Figure 9
Antimicrobial activity of WBF5 and WBF6 against E. coli, E. faecalis, C. perfringens, and P. aeruginosa.
See this image and copyright information in PMC

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