Weed wars: The hidden costs of herbicide use in rice

Herbicides have become a double-edged sword for Indian farmers. On one hand, they have been a lifesaver, making it easier to control pesky weeds that steal nutrients and water from crops. They play an important role in adoption of direct seeded rice, which reduces labour costs by up to 40%.

With less time spent battling these unwanted plants because of herbicide use, farmers have enjoyed some relief from backbreaking labour. However, the story doesn't end there. The widespread application of herbicides has raised several concerns. “Overreliance on one type of herbicide or faulty way of application can lead to herbicide resistance development in weeds,” as per the National Rice Research Institute, Cuttack.

Environmentally, herbicides can seep into the soil, contaminating groundwater and reducing soil fertility. Runoff from agricultural fields can carry these chemicals into water bodies, harming aquatic life. Herbicides also disrupt ecosystems by killing beneficial insects and plants, leading to biodiversity loss.

Human health is another major concern. Accidental ingestion of herbicides can result in severe health issues, while long-term exposure has been linked to cancer, reproductive problems, and neurological disorders. Additionally, herbicide residues in food pose risks to consumers.

Economically, herbicide use can be costly for farmers, as the development of herbicide-resistant weeds often necessitates the use of more expensive chemicals. Overreliance on herbicides can also limit the diversity of farming practices, making farmers vulnerable to price fluctuations. From a social and ethical perspective, herbicides exacerbate socioeconomic disparities as they are often expensive and inaccessible to small farmers.

Glyphosate and 2,4-D: Herbicide concerns

Glyphosate is a widely used herbicide employed in various agricultural sectors, including rice cultivation. While often considered less toxic than older herbicides, its environmental impact remains a subject of contention. Concerns encompass its role in fostering herbicide-resistant weeds, harming beneficial insects, and contaminating water bodies. The International Agency for Research on Cancer has classified glyphosate as a probable carcinogen, although other regulatory bodies hold differing opinions. Ongoing research aims to elucidate the potential health risks associated with glyphosate exposure.

2,4-D, another prevalent herbicide in rice farming for broad-leaf weed management, shares similar environmental concerns with glyphosate. Its potential to contaminate water bodies, harm aquatic life, and contribute to herbicide resistance has raised alarms. Additionally, exposure to 2,4-D has been linked to respiratory issues, skin irritation, and hormonal disruptions.

It is crucial to recognise that the environmental and health impacts of these herbicides can fluctuate based on factors such as application methods, rates, and local conditions. Moreover, the emergence of herbicide-resistant weeds due to the extensive use of glyphosate and 2,4-D has become a pressing issue for farmers, prompting increased reliance on alternative herbicides and potentially aggravating the problem.

Objections to herbicides in India

In June 2024, the Indian Council of Agricultural Research (ICAR) released two herbicide-tolerant  basmati rice varieties for commercial cultivation. These varieties are designed for use in direct-seeded rice systems, where seeds are sown directly in the field instead of transplanting seedlings.

Direct-seeded rice in particular presents unique challenges for weed management compared to traditional puddled transplanted rice. The absence of puddling eliminates the initial advantage of flooding to suppress weeds. Additionally, the smaller size differential between rice seedlings and weeds in direct-seeded rice makes early weed control difficult. This creates a conducive environment for rapid weed growth and establishment, significantly impacting rice yield and quality. This makes it tough for farmers to protect their crops and get a good harvest.

“Both the varieties have been given all statutory clearances, including by the Central Insecticides Board & Registration Committee and Food Safety and Standards Authority,” Ashok Kumar Singh, the chief breeder, said as per a report in the Hindustan Times.

While ICAR promotes these herbicide-tolerant varieties as beneficial for farmers, several organisations have raised significant concerns. A  letter has been shared with the Union Minister for Agriculture & Farmers’ Welfare recently in this regard. The letter is signed by a diverse group of individuals, including Kavitha Kuruganti, a prominent social activist associated with the Alliance for Sustainable & Holistic Agriculture (ASHA-Kisan Swaraj) advocating for sustainable farming, P. Duraisingham, a representative of consumer interests, and Soma Marla, a scientist with a background in ICAR.

Concerns about herbicide-tolerant Basmati rice varieties

• Chemical dependence and contradiction with government policy: ICAR claims these varieties are non-GM, but they were developed through mutagenesis using a chemical and are tolerant to the herbicide Imazethapyr. This heavy reliance on herbicides contradicts the government's push for promoting sustainable and non-chemical agricultural practices. Critics argue that ICAR's approach undermines efforts to transition towards organic or minimal-chemical farming.
• Environmental and health risks: The use of Imazethapyr raises concerns about potential environmental damage. This includes the development of herbicide-resistant superweeds, which would require even stronger chemicals for control. Increased herbicide use can also disrupt soil ecology and harm beneficial organisms. The letter highlights potential health risks for farmers and agricultural workers exposed to Imazethapyr during spraying and field work. These risks can include skin irritation, respiratory problems, and potential long-term health effects.

Economic concerns for farmers: The letter argues that increased reliance on herbicides like Imazethapyr could lead to higher costs for farmers. Farmers may need to purchase not only the herbicide-tolerant seeds but also the herbicide and potentially additional chemicals to manage resistant weeds. The letter also expresses concern about the potential loss of farm-level sovereignty. With reliance on specific herbicide-tolerant seeds and herbicide combinations, farmers may become dependent on corporations that control these products.

• Regulatory issues and lack of testing: The letter questions the legality of promoting Imazethapyr for use on paddy, as it is not currently registered for this crop in India. This raises concerns about the potential health and environmental risks associated with off-label use of herbicides. Additionally, the letter criticises the lack of regulations and scientific protocols for testing the safety of herbicides on herbicide-tolerant crops. This includes protocols for establishing safe residue levels in food produced from herbicide-tolerant crops.
• Impact on Basmati rice exports: The letter warns that importing countries with strict pesticide residue regulations may reject Indian basmati rice if residues of Imazethapyr are detected. This could have a significant negative impact on India's basmati rice exports, a valuable source of income for farmers.
• Public resistance and potential legal challenges: The letter highlights the potential for strong resistance from farmers and consumers who are concerned about the environmental and health risks of herbicide-tolerant crops. It warns that if the government does not withdraw these herbicide-tolerant basmati varieties, there could be legal challenges through Public Interest Litigation (PIL). These PILs could focus on violations of regulations, potential health risks, and the right to safe food.

These concerns underscore the need for a more cautious approach to developing and deploying new agricultural technologies. It is crucial to prioritise sustainable practices, ensure thorough safety testing, and address regulatory gaps before introducing new technologies like herbicide-tolerant crops.

To effectively manage weeds in direct-seeded rice systems, a proactive and comprehensive approach is imperative. The challenges posed by direct-seeded rice, such as the absence of puddling and the rapid growth of weeds, necessitate strategies that extend beyond traditional herbicide reliance. By implementing preventive measures, farmers can significantly reduce weed populations, mitigate environmental risks, and enhance the overall sustainability of their cropping systems.

These measures encompass a range of practices aimed at limiting weed seed dispersal, production, and establishment, including early weed control, crop rotation, the use of competitive cultivars, seed predation enhancement, the stimulation of fatal germination, and physical barriers like mulching and cover crops.