Thursday, May 30, 2024

A weed with many uses

In a world-first study, researchers at the University of South Australia (UniSA) screened 50 native plants and weeds to find a cheaper and more environmentally friendly source for the bulk producing urease enzymes, used to strengthen soil and help to prevent erosion. Plant-based urease enzymes are becoming a popular alternative to cement, lime or artificial soil binders because they are natural and not damaging to the environment. One kilogram of cement produces one kilogram of carbon dioxide, making the construction industry one of the highest CO2 emitters. It is estimated that the production of Portland cement, the most used material for construction and soil strength improvement, contributes about 5–7% of total global anthropogenic carbon dioxide emissions.

Among the weeds tested, paddy melon, Cucumis myriocarpus, ticked all the boxes and was almost as effective as soybean enzymes, which are more expensive and used primarily for food. Paddy melon, originally from Southern Africa, and probably introduced when camels were brought in as a means of inland transport in the late 1800’s, is a very widely naturalised weed. It has a range from south eastern Northern Territory to Tasmania.

According to the researchers at the UniSA, compared to the production of commercial enzymes, paddy melon enzymes are cheaper, more sustainable, and more efficient than other enzymes used to cement and stabilise soils.

“Not only have we found a natural alternative to other commercial enzymes, but we could solve a very expensive problem for the agricultural industry by harvesting these weeds, reducing the availability of seeds for spreading, preserving biodiversity and growing paddy melon as a commercial crop. The construction, forestry and mining industries all stand to benefit from this research, but another unexpected winner could be some First Nations communities,” said UniSA geotechnical engineer, Professor Mizanur Rahman.

“Paddy melon is an invasive weed on many Native Title lands and soil erosion is another major issue. Our discovery has the potential to address both concerns and support biodiversity conservation or rehabilitation.”

The paddy melon enzymes could also be used to stabilise tailing dams and cap them with a thin natural crust, preventing toxic waste material from escaping. In forest plantations herbicide is normally applied at the base of commercially grown trees to keep weeds under control.

“Herbicide is not only harmful to the environment, but weeds often develop a resistance to these chemicals,” Prof Rahman says. “Spraying paddy melon enzyme solution around the trees would create a thin crust, preventing weeds completely. In essence, we are using a weed to control a weed.”

Prof Rahman says the feedback from industry sectors has been very positive.

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