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Al-Juthery, et al.

more effective delivery to the rhizosphere. Some studies trials to assess long-term impacts on soil quality indicators
have reported that nano-biofertilizer application leads such as organic carbon content and microbial diversity.
to higher soil enzyme activities and microbial biomass Such data will be critical in establishing whether nano-
compared to conventional treatments, indicating a biofertilizers can sustain or even improve long-term soil
stimulated soil microbiome alongside crop growth health compared to traditional biofertilizers.
promotion. Over multiple growing seasons, this may
translate into improved soil structure and nutrient 5. Nano-biofertilizer manufacturing
cycling. However, definitive long-term field studies are technologies
still limited. One concern is the potential for negative
effects on soil properties from the accumulation of Nano-biofertilizers can be manufactured using several
nanoparticles (e.g., heavy metal buildup or pH shifts). methods, as outlined in Table 4, which integrate
So far, short- and medium-term field data are promising, nanotechnology with biological agents for nutrient
showing maintained or improved soil fertility and no delivery, thereby supporting sustainable agriculture.
adverse effects on soil biota, but ongoing monitoring is
necessary. Farmer adoption of nano-biofertilizers may 5.1. Encapsulation with nanomaterials
ultimately depend on their consistent field performance Encapsulation is one of the most widely used
across varied environments. While traditional manufacturing techniques for nano-biofertilizers. In this
biofertilizers can fail under suboptimal field conditions approach, microbial inoculants or nutrient formulations
such as drought or poor soils, nano-biofertilizers have are enclosed within nano-sized carriers, often made
demonstrated greater resilience by continuing to release from biopolymers such as chitosan, alginate, or starch.
nutrients and support microbial activity even under This method improves the stability and viability of
stress. For instance, polymer-encapsulated biofertilizer microbial strains and allows for the gradual release of
nanoparticles can stabilize microbes against heat and nutrients into the rhizosphere.
desiccation, delivering better results than free microbial A practical example is the use of chitosan–alginate
inoculants. This suggests that nano-based formulations nanocapsules embedded with nitrogen-phosphorus-
may provide more reliable long-term benefits in potassium nutrients and plant growth-promoting
heterogeneous field environments. Overall, nano- rhizobacteria, which have been successfully employed
biofertilizers appear to match or exceed conventional in field trials. The inclusion of humic acid as a cross-
biofertilizers in enhancing crop yields while also linker produced porous capsules with extended nutrient
sustaining soil health. They combine the slow-building availability and improved root colonization. These
advantages of biofertilization with the rapid nutrient nanocapsules can be applied as soil granules, seed
availability offered by nanotechnology. Nevertheless, coatings, or foliar sprays. Uniform-sized beads can be
agronomists emphasize the need for more multi-season produced using a sodium alginate–calcium chloride

Table 4. Summary of common nano-biofertilizer manufacturing methods, along with references to
relevant studies
Manufacturing method Description References
Encapsulation with Biofertilizers are encapsulated within nanomaterial coatings, such as chitosan 49
nanomaterials and alginate crosslinked with humic acid, to improve stability and controlled
nutrient release
Green synthesis using Microorganisms such as bacteria, fungi, and algae are used to biosynthesize 52
microorganisms nanoparticles, which are then combined with biofertilizers. This eco-friendly
approach leverages the natural reducing agents produced by these organisms
Chemical methods Chemical techniques such as sol-gel and hydrothermal methods are employed 53
(e.g., sol –gel, to synthesize nanoparticles, which are then integrated with biofertilizers. These
hydrothermal) methods allow for precise control over particle size and composition
Top-down and bottom-up Top-down approaches involve breaking down bulk materials into nanoparticles, 1
approaches while bottom-up approaches assemble nanoparticles from atomic or molecular
components. Both methods are used to create nano-biofertilizers with desired
properties

Volume 22 Issue 3 (2025) 20 doi: 10.36922/AJWEP025160123