Dr Tan Wee Kee (Science ’99) from NUS Environmental Research Institute shares the details behind a patented innovation that can change how — and where — plants can be grown.
With clean water available to us at just a turn of the tap, it might not be apparent to most Singaporeans that a water crisis looms over the globe. According to the World Health Organization (WHO), half of the planet’s population will live in areas with permanent water scarcity by 2025.
With 72% of Earth’s finite fresh water supplies being used for agriculture, finding ways to improve the efficiency of water usage is critical to solving this issue of scarcity. This is especially so, considering how a substantial amount of irrigated water for agricultural use is lost through evaporation, leaching or percolation into soil layers too deep for plants to absorb. While irrigation technologies, such as sprinklers and drip systems, have been developed to optimise how water is dispensed, an NUS team has approached the issue from a different angle — and it is tackling the problem from the ground up, literally.
Gelling with the Zero-waste Narrative
Enter InnoGro — a patented super-absorbent hydrogel derived from soy, developed by Dr Tan Wee Kee and Dr Zhu Jingling from NUS Environmental Research Institute (NERI). With the ability to swell to over 150 times its size, InnoGro can absorb water hundreds of times its dry weight. This allows it to act almost like mini-reservoirs, keeping moisture within the soil, and within reach of plants for longer periods of time. Adding InnoGro to soil as a supplement has been found to reduce water wastage by up to 75%.
The positive environmental impact it makes goes beyond water usage. With better water retention in the plant’s growing medium, watering frequencies can be cut down by 70%, translating to much more energy-efficient farming practices. By holding water, InnoGro also helps to retain nutrients. Studies have shown that up to 90% of phosphorus, 70% of potassium and 70% of nitrogen from fertilisers are lost to the environment, which can translate to environmental pollution. By just adding a 5% hydrogel supplement to the growing substrate, leaching can be cut down by about 30%.
Yet InnoGro is a game-changer in even more ways. “Hydrogels are not new,” highlights Dr Tan. “However, while most are petroleum-based, ours is developed from plant waste, making it a bio-based and sustainable product.” While there are other hydrogels derived from other ‘virgin materials’, such as cellulose, InnoGro is one of the few products on the market to boast waste-to-resource credentials.
The humble base ingredient of InnoGro is okara, the Japanese term for soy pulp: the insoluble parts of a soybean that are left behind in the production of soy milk and beancurd. While one might find them incorporated into some traditional Japanese dishes, okara — which is generated in considerable quantities given the amount of soy food items that are produced — is generally considered food waste; and some 10,000 tonnes of of it are produced in Singapore each year. “Okara has been a pain for the food manufacturing industry,” shares Dr Tan. “But once it undergoes a conversion step into a hydrogel, its water-capturing properties will be impressive. Recognising this, Professor Ong Choon Nam (Science ’72), the former Director of NERI, started discussions with Professor Li Jun (Affiliate Alumnus ’19), from the Department of Biomedical Engineering, who was working on hydrogels for biomedical fields.” This was in 2016. By 2019, the team had developed a patented synthesis technology with 100% conversion of the whole waste into hydrogel — with zero residue. This process involves purging a homogenised aqueous suspension of okara by nitrogen gas, and heating it at a sustained temperature and constant pressure while initiating a radical polymerisation reaction. The resultant product is then dried and milled into powder. Patents for this technology to produce InnoGro have also been filed at the national level, and countries filed include Singapore, Malaysia, Indonesia, China, Japan and the United States.
Powering Plant Growth
Apart from its unique proposition as a sustainable waste-to-resource product, InnoGro also stands out as the only hydrogel soil supplement with studies that back up its effect on the growth of leafy vegetables from seedling to harvest stage. “My role has been in demonstrating and defining how this okara-derived hydrogel can enhance the growth of plants, and be applied in various agricultural set-ups,” says Dr Tan. The difference is especially marked for plants growing in water-scarce environments: the addition of InnoGro has been shown to result in a 113% increase in shoot weight at harvest, 57% increase in total leaf area, and 50% increase in relative growth rate in water-limited conditions. With water deficit as the factor leading to more than 40% of crop losses reported worldwide, InnoGro stands to be the agricultural industry’s ally in combating the food security threat that droughts bring.
At present, Dr Tan’s team is taking InnoGro out to the world. “We were awarded a grant from Enterprise Singapore to do more field trials to obtain Proof of Concept. And apart from gathering data, the next stage is to send more samples for people around the world to try InnoGro. Recently, we sent samples to the Middle East,” she shares, adding that the product can be used in the agriculture and horticulture sectors, as well as in landscaping. “For example, we’ve explored the possibilities of using InnoGro for maintaining landscaping displays, especially in situations where it is not possible to integrate an irrigation system. We are still looking for the sweet spot in the market for the hydrogel.” In anticipation of demand, the NuSoil team is also utilising a reactor to shorten the synthesis process from 24 hours to just five hours, and upscaling the output from 200g in two weeks in a lab setting to ten kilograms per week.
While the market potential of this product could be enormous, Dr Tan is focused not just on InnoGro, but other innovations and their benefits to mankind. “I am ultimately a plant lover. I am always looking at ways to improve yields and how to grow food production under conditions of limited natural resources,” she enthuses, adding that she is also exploring on innovations that could benefit people living in places where food crops could not be grown previously. “And if you think about hydrogels as an alternative medium for plants to grow in, perhaps one day we might be able to bring this technology to outer space — and our astronauts might even be able to harvest food. It would probably be a very costly exercise, but one can always dream!”