Toxic, Invasive Weed finds Value as Organic Fertiliser

Mar 29, 2022

The toxic, invasive herb Ageratum conyzoides, or billy goat weed, can be bio-converted into nutrient-rich compost for crop cultivation, says a new study.

Published March in the journal Biomass Conversion and Biorefinery, the study found the compost environmentally safe and ideal for use as soil conditioner to improve farmlands.

Krishna Chaitanya Maturi, an author of the study and researcher at the Indian Institute of Technology (IIT) Guwahati, says that the adverse impact of the A. conyzoides weeds, especially in degrading soil quality by reducing useful soil organisms, is well documented. The invasive weed, commonly referred to as billy goat weed and chick weed, is a native of South America.

"It is an extremely toxic plant which contains various toxic allelochemicals such as stigmasterol, demethoxy-ageratochromene, and caryophyllene due to which A. conyzoides is harmful to neighboring crops. It also disrupts various aboriginal plant cultures in diverse ecological regions," Maturi tells SciDev.Net.

Ajay S. Kalamdhad, co-author and professor of Environmental Engineering at IIT, says that the study aimed to produce a non-toxic product by biologically treating the plant, blending it with inoculums (combination of microorganisms and organic matters) and bulking agents in a rotary drum composter.

"The composter was competent in increasing nutritional parameters such as nitrogen, phosphorus and potassium while decreasing lignin, hemicelluloses and cellulose," says Kalamdhad. "The utilization of A. conyzoides for the in-vessel composting technique is a novel approach for getting a value-added product, which is rarely reported in other management technologies."

According to Kalamdhad, statistical analysis showed close relationship between biodegradation and nutritional products, following composting. "As a result, the study suggests that A. conyzoides compost can be used in a variety of farming applications that require a nutrient-rich, non-toxic product that is environmentally acceptable," he added.

According to an FAO paper, the value of A. conyzoides in boosting soil fertility is part of indigenous knowledge among farmers in the mid-hills of Arunachal Pradesh. The paper explains that farmers in Arunachal Pradesh believe that the plant can be used to increase rice grain yields through improving the chemical properties and fertility of soils.

K.C. Jisha, an assistant professor at the Muslim Education Society College in Kerala who was not involved in the study, says the findings would be of value to agro-industry policymakers looking for effective weed management strategies. "The compost of A. conyzoides can be used as a substitute for chemical fertilizers," she tells SciDev.Net.

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Video: From Conventional to Regenerative: Will Groeneveld’s Journey Back to the Land

"You realize you've got a pretty finite number of years to do this. If you ever want to try something new, you better do it."

That mindset helped Will Groeneveld take a bold turn on his Alberta grain farm. A lifelong farmer, Will had never heard of regenerative agriculture until 2018, when he attended a seminar by Kevin Elmy that shifted his worldview. What began as curiosity quickly turned into a deep exploration of how biology—not just chemistry—shapes the health of our soils, crops and ecosystems.

In this video, Will candidly reflects on his family’s farming history, how the operation evolved from a traditional mixed farm to grain-only, and how the desire to improve the land pushed him to invite livestock back into the rotation—without owning a single cow.

Today, through creative partnerships and a commitment to the five principles of regenerative agriculture, Will is reintroducing diversity, building soil health and extending living roots in the ground for as much of the year as possible. Whether it’s through intercropping, zero tillage (which he’s practiced since the 1980s) or managing forage for visiting cattle, Will’s approach is a testament to continuous learning and a willingness to challenge old norms.

Will is a participant in the Regenerative Agriculture Lab (RAL), a social innovation process bringing together producers, researchers, retailers and others to co-create a resilient regenerative agriculture system in Alberta. His story highlights both the potential and humility required to farm with nature, not against it.