A group of scientists from the National University of Singapore (NUS) have developed an innovative solution that has the potential to revolutionise modern farming. As opposed to conventional farming methods where crops are fed and grown through soil application, which is an aspect that tends to contribute to wastage and inefficiency, this group of scientists has come up with an innovative microneedle fertiliser delivery method to provide crops with this essential resource.
Conventional fertilisation practices would involve introducing biofertilizers, which are beneficial bacteria and fungi that enhance nutrient uptake and stress resistance in plants. However, once biofertilizers are introduced into the soil, they encounter significant challenges, including competition with the existing soil microbiota, managing soil pH, and developing resistance to any factors that may limit their effectiveness. Most fertilisers end up unused by the plant roots, which would be their most desired location, ultimately leading to wastage of resources and environmental degradation.
By contrast, the microneedle system developed by the NUS team is an entirely different approach altogether. It is modelled on microneedle technology developed for a biomedical application where substances are precisely delivered into tissue without pain and involves using dissolvable microneedle patches to inject living biofertiliser directly into the leaf or stem.　In greenhouse experiments carried out using vegetable crops such as choy sum and kale, plants treated using the microneedle patch grew faster, as evidenced by their biomass, leaf area and plant height, using over 15% less biofertiliser than plants grown using conventional soil inoculation.
The patches containing the microneedles are made of polyvinyl alcohol, which is a low-cost and biodegradable substance, and these patches have a different design to cater to leaf surfaces or to stems, which are shaped in the form of pyramids that are small enough to just pierce the surfaces of the plants without damaging them. The technique of applying them is either done by hand or by the use of a small device that ensures equal pressure is applied, and they start to dissolve within one minute to release microbes found inside them to the vascular plant.
One of the most interesting things about this technology is its level of precision. Because the dose is so closely proportional to the number of microbes in the patch, growers are able to precisely determine just how much biofertiliser is being supplied to each plant, something which is difficult to accomplish via soil application. This ability not only increases efficiency but also cuts waste and cost, which is particularly useful in urban farm setups because land is at such a premium.
Aside from the immediate benefits to growth, the researchers from NUS found that ‘the microbes tended to migrate from the entry site towards the root region within a few days, assimilating into the existing root microbiota without affecting its overall composition.’ Once established, they impacted plant internal physiology, improving nitrogen nutrition efficiency, activating central metabolic pathways, and inducing the production of compounds involved with plant growth and stress responses.’ Plants receiving treatment with microneedle-delivered ‘biofertiliser showed higher antioxidant activity’, indicative of their possible resilience against stress in their surrounding environment.
The team went on to further extend the application by including beneficial fungi with very positive outcomes, too. The patches with high concentrations of the fungus known to affect the level of plant phytohormones have been shown to uphold the correct phytohormone equilibrium in the plant. It is an indication that the use of microneedle technology may very well facilitate the utilisation of other beneficial microbes for plants.
The early applications would most likely be concentrated on high-value crops and controlled environments where every penny spent on inputs is valuable. Nevertheless, the researchers have already begun looking into ways in which they can develop larger applications using their system. Combining their microneedle system with agricultural robotics would enable the application process in larger fields, which would make precision applications more mainstream.
When considering the current state of the agriculture industry and its double burden of both sustainability and productivity, inventions such as the microneedle biofertiliser system provide insight into what the future could look like. Providing the right nutrients at the right time in the right location can help reduce waste, decrease costs, and ensure healthier produce—all while providing a sustainable alternative to traditional fertilisers.
