Introduction:
People always talk about how we should prevent soil erosion and pollution in farming while being more mindful about chemical residues in soil that come with the aggressive use of chemicals. That is why the idea of organic herbicides is gaining popularity among farmers and is seen as an alternative to chemical-based herbicides. But are these natural weed control methods practical? Are they as effective as chemical-based herbicides? Can natural herbicides be used by farmers everywhere?
In this blog, you will find everything you need to know about organic herbicides, including what they are, common types of organic herbicides available in India, their major benefits, and, most importantly, whether organic herbicides actually work on weeds or not? So let’s get started.
What are Organic Herbicides?
Organic herbicides are natural compounds utilized to control weeds or eradicate them. They are made from natural sources like plant oils, citric acid, vinegar, and other biodegradable compounds.
While synthetic options may work faster or yield stronger results, organic herbicides are used for soil and farm health, as well as residue-free usage. They work topically, damaging the weed plant tissues externally, while also suppressing their growth. These are best recommended and used in organic farming, where the focus is on selling naturally grown crops, fruits, and vegetables.
How do Organic Herbicides Work?
Organic herbicides work differently than chemical-based herbicides. Most natural products work by interfering with the plant’s surface, damaging the cell wall or drying it out.
These effects are usually seen after direct contact with the weed’s stems or leaves. While chemical herbicides often move within the plant (systemic action), a natural herbicide for farm use works in a non-systemic manner, affecting only the areas it touches.
Some eco-friendly organic herbicides are acid-based or oil-based. For example, acids like vinegar or essential oils like clove oil can be effective against the soft leaves of a weed. But these options can show results with multiple applications and are most effective on newly sprouted or young weeds.
Here, the timing of application also plays a crucial role in organic farming and weed management. Apply these natural options while the weeds are still small and actively growing.
Types of Organic Herbicides
Many natural weed control methods are now easily available for Indian farmers. While not as aggressive or fast-acting as chemical herbicides, these organic herbicides serve a strong role in eco-farming systems.
Here are the best organic herbicides in India that farmers can use to reduce the growth of annoying weeds:
Vinegar-based Herbicides:
The acetic acid (naturally found in vinegar) causes the plant’s surface to burn and dehydrate. It works really well on young weeds. You can prepare homemade vinegar sprays with 15 to 20% acetic acid concentration using locally fermented products.
Citric Acid-based Herbicides:
Citric acid can break the plant cell’s walls down. Many organic products contain a mix of acetic and citric acids for stronger action. You can use peels from citrus fruits and vegetables like lemons, sweet limes, and oranges and ferment them to naturally extract citric acid.
Clove Oils and Other Essential Oils:
These oils can remove the protective wax-like layer off from the plant leaves, which leads to drying. Clove oil, eucalyptus oil, and lemongrass oil (aka. Citronella oil) are a few examples of essential oils used as organic herbicides. Locally sourced neem oils also work best for weed control.
Soap-based Sprays:
Some herbicides contain potassium salts from fatty acids that break down the plant tissues. These are often combined with oils for a better effect. Potassium laureate and potassium oleate, found in fatty acids, are often blended with essential oils to work on soft-stemmed weeds.
Biological Herbicides:
These organic herbicides target specific weeds with fungi or bacteria, thereby harming only the targeted weeds without affecting commercial crop plants.
Although still in development or research, this type shows tremendous potential. Phoma macrostoma is a fungus that targets weeds and is being developed in international labs.
An ICAR and IARI based research on Trichoderma spp. Fungi and Pseudomonas fluorescens bacteria undergo in-depth analysis of biological herbicides, which can be particularly useful for rice and pulse cultivation.
In most cases, a natural herbicide used on farms falls under the category of topical or contact-only action. These organic herbicides may need repeated applications for effective results, especially during the rainy season.
What are the Benefits of Herbicides in Weed Control Practice?
Organic herbicides support sustainable farming methods while also improving the soil’s health. In corn (maize) fields, organic mulches like groundnut shells and mango leaves, or corn gluten meals, can control weeds and boost yield. These natural weed control methods also save input costs and improve profits in agriculture.
Apart from that, there are many clear advantages of organic herbicides, especially for those farmers who are committed to soil health and sustainable practices. Here are a few of them:
Soil and Water Safety:
Organic herbicides can break down easily and also don’t release harmful chemicals into the groundwater or soil. This maintains the soil’s fertility for upcoming crops and makes sure that the water sources are clean and safe for consumption by cattle or humans.
No Residue Issues:
Natural herbicides do not leave harmful residues on crops, unlike chemical alternatives. This is particularly important for certified organic farms, where products must be residue-free. This is vital for gaining the trust of consumers and export markets.
Safe for Labour:
Since most organic herbicides are non-toxic, there is a low health risk for farm workers during the application process. You can apply them even without heavy protective gear, which in turn reduces any health hazard caused by something like a herbicide, in your fields.
Reduce Herbicide Resistance:
Weeds do not build an early resistance to natural formulations because the action is generally physical or topical. The weeds take much longer to build resistance, which means natural herbicides can stay effective for a longer period of time.
Overall, these eco-friendly herbicide alternatives give long-term benefits. This is especially true for small to medium-scale organic farms.
“Although still in development or research, this type shows tremendous potential. Phoma macrostoma is a fungus that targets weeds and is being developed in international labs. In India, Trichoderma spp. and Pseudomonas fluorescens are being researched by ICAR and IARI for the cultivation of rice and pulses.”
Challenges and Limitation of Organic Herbicides
Eco-friendly herbicides are effective only on plant surfaces, requiring frequent applications and increased labor costs. Vinegar, fatty acid sprays, and clove oils effectively target the upper parts of weeds, but do not kill the roots.
While the benefits of these organic herbicides are promising, safe, and real, it is also essential to understand their limitations before choosing them. Here are a few challenges linked to their usage:
Frequent Application:
Organic herbicides typically require repeated applications for optimal effect, especially on mature weeds. Being completely natural, they are milder, which needs 2 to 3 waves of spraying to show even the slightest effects.
Less Effective on Deep-Rooted Weeds:
Since the action is topical, deep-rooted weeds like nutgrass or wild amaranth may quickly bounce back. Unlike chemical options, they cannot reach the internal mechanism of a weed plant and kill it from within. Hence, stubborn weeds eventually need a hand of chemical options.
High Cost per Acre:
Some best organic herbicides in India are costly per litre, than the synthetic options. Eg: essential oils. So switching to natural or organic alternatives is impractical, if you have a larger area and are not seeking an organic label.
Slow Results:
Farmers who are used to fast results can find organic options slow and effort-taking. Their mild effect takes time to show results, so if there is a huge wave of rigid weeds that need immediate action, an organic herbicide might not be the best solution.
Weather Dependancy:
Higher humidity or rain can reduce the effectiveness of organic herbicides. They show the best results in dry weather.
Therefore, an inconvenience arises if you have to wait for the rain or wind to stop. This could increase moisture and potentially lead to fungal infections.
Despite these limitations, organic herbicides remain vital for weed management in organic farming, especially when integrated with mulching and hand-picking.
When to Use Organic vs Chemical Herbicides?
Farmers should make informed choices, based on factors such as crop type, weed pressure, and their farming style.
Organic Herbicides:
Choose organic herbicides when growing crops such as vegetables, fruits, or pulses under organic certification. If your field is small to medium-sized and labor is available, you can also use organic herbicides in that case.
Additionally, if the weed pressure is light to moderate and you need an eco-friendly herbicide alternative with zero residue, consider organic herbicides. And in the end, when your crop is a premium-priced product for being chemical-free, organic herbicides are your best options.
Chemical Herbicides:
You can choose chemical-based herbicides when weed growth is aggressive and manually controlling the situation is impossible. You can also choose chemical- based herbicides when you are managing a large single-crop field of wheat, cotton or paddy. If you need systemic action for perennial and rigid weeds, these chemical-based options can deliver your desired outputs.
Furthermore, when rains make the organic herbicides ineffective, adopting chemical-based herbicides is recommended. Lastly, if you aren’t seeking an organic certification to sell your product in the market, it is rather practical to use chemical-based herbicides.
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