Neem & Agriculture

The National Research Council in the United States has placed the neem tree in their top ten list of plants to be studied and used for the sustainable development of the human race and the planet. With mankind’s pervasive use of synthetic and toxic pesticides in agriculture, organic products are urgently needed for their positive environmental impact. As the only naturally derived biocide formally accepted by the European Union, neem’s relevance in the agricultural sector is increasing. With neem oil containing over two hundred biologically active compounds, alongside the growing interest in organic products worldwide, neem’s reputation as a valuable resource will only intensify.

The Organic Alternative for Crop Protection

Traditionally, the agricultural industry has relied on chemical pesticides for its crops, but 98% of pesticides sprayed end up on a different destination than that intended, resulting in the pollution of plant life, animals, insects, and water [1]. It also ends up building harmful toxins in the atmosphere.

The neem tree fulfills the requirements for low carbon agriculture, serving as an entirely natural and effective pesticide in crop protection.

The Extension Toxicology Network, a co-operative of the University of California, Cornell University, and Oregon State University, states that the active ingredient in neem, azadirachtin, is an organic alternative to synthetic and toxic pesticides [2]. Rather than acting as a poison, which is the case with many other pesticides, azadirachtin is processed by insects much like a natural hormone and introduces antifeedant, repellent and growth inhibiting behavior [3]. Neem oil is also proving to be an effective fungicide for the prevention and control of many plant diseases such as powdery mildew, black spot, down mildew, rust, leaf spot and botrytis [4].

At a utilitarian level, neem offers a cost effective and non-toxic alternative to a number of synthetic pesticides. Effective against more than 600 species of insects, neem oil acts on the hormonal systems of pests and therefore does not lead to the development of resistance in future generations [5]. The ability to use neem as a pesticide that doesn’t damage the soil will have a long-term positive impact on farmers and their farmland, whether or not they cultivate crops organically.

Neem’s Strength as an Organic Pesticide

Effectiveness & Persistency

Neem extracts do not kill pests immediately, but impact the feeding or life cycle of the insect until it is no longer able to live or reproduce [6].

Environmentally Friendly

Neem based pesticides are entirely biodegradable, leaving no residue on the land. The degradation of azadirachtin occurs due to the effects of UV light, temperature, pH and microbial activity, and therefore will not accumulate in the soil. According to the US National Pesticide Information Center (NPIC), neem-based pesticides are practically non-toxic to birds, mammals, plants and pollinators [7].

Increases Nutritional Value

Organic foods contain between 20-40 percent higher levels of nutrients, including vitamin C, zinc and iron that are very important in maintaining a healthy body [8]. They also contain up to 60 percent more antioxidants than non-organically grown foodstuffs, which helps to prevent and repair damage to the body’s tissues from free radicals [9].

Immune to Resistance

As opposed to synthetic pesticides, neem-based pesticides have multiple modes of action against insects, and therefore rarely induce resistance. Neem acts on the insect’s hormonal system, not on the digestive or nervous systems, which makes it very difficult for future generations of insects to develop any resistance [10].

Cost Effective

Neem-based pesticides are cost effective when compared to traditional synthetic pesticides.

A By-Product that Nourishes Soil

Seeds that have been crushed to produce neem oil do not go to waste. When dried, the resultant ‘cake’ contains nutrients that work as an organic pesticide and fertilizer that provides nourishment for soil.

Neem oil and cake can help retain water for the soil and improve its porosity as well as protecting the roots from plagues and illnesses. Neem cake inputs more nitrogen, phosphorous, potassium, calcium and magnesium than common manure, making it ideal food for micro-organisms. Finally, because organic products need to break down before releasing their nutrients, as well as the fact that neem degrades after 3 days of exposure to UV light, pollution and runoff are reduced to a minimum.

Neem strengthens the organic content in the soil by reducing its alkalinity and producing organic acids on decomposition [11]. Being completely natural, neem is compatible with soil microbes, nurtures healthy bacteria and ensures stronger texture, higher water holding capacity and aeration in the soil, all contributing towards better root development [12].

Neem makes the soil more fertile due to an ingredient that blocks soil bacteria from converting nitrogenous compounds into nitrogen gas. As a nitrification inhibitor, neem prolongs the availability of nitrogen to both short duration and long duration crops [13].

Neem’s Strengths as an Organic Fertilizer

Improves Soil Health

Helping the soil retain moisture and increases workability, organic fertilizers such as neem increase airflow through the soil, which allows the plants’ roots to breathe.

Environmentally Friendly

Organic fertilizers such as neem are healthier for the ecosystem because they must first break down before releasing their nutrients, ensuring that no runoff occurs.

Strengthens hydraulic conductivity

Organic matter supplied by organic fertilizers such as neem improves water flow in soils and provides a food source for soil micro-organisms which contribute to macro-pore formation.

[1] Natural Resources Defense Council. Pesticides – What You Need to Know (2014) 
[2] Extoxnet. Extension Toxicology Network Pesticide Information Profiles (2016) 
[3] Copping, L.G. The BioPesticides Manual. Second Edition. British Crop Protection Counsel (2001)
[4] Environmental Protection Agency Fact Sheet. Azadirachtin - Clarified Hydrophobic Extract of Neem Oil(2000) 
[5] Lowery, D.T. and M.B. Isman. Effects of Neem and Azadirachtin on Aphids and their Natural Enemies. In Bioregulators for Crop Protection and Pest Control. American Chemical Society (1994) 
[6] National Research Council. Neem: A Tree for Solving Global Problems. The Minerva Group (2002) 
[7] Koul, Opender, and Seema Wahab, eds. Neem: Today and in the New Millennium (2004) 
[8] Dangour, Alan D., et al. "Nutritional quality of organic foods: a systematic review." The American journal of clinical nutrition 90.3 (2009): 680-685. 
[9] Brandt, Kirsten, and Jens Peter Mølgaard. Organic agriculture: Does it Enhance or Reduce the Nutritional Value of Plant Foods?." Journal of the Science of Food and Agriculture 81.9 (2001). 
[10] Nisbet, Alasdair J. Azadirachtin from the Neem Tree: Action Against Insects." Anais da Sociedade Entomológica do Brasil (2000).
[11] Ramachandran, Sumitra, et al. Oil Cakes and their Biotechnological Applications–A review."Bioresource technology 98.10 (2007) 
[12] Kumar, Ajay, et al. Organic Margosa: An Agent of Biodynamic Agriculture. World 362.360.2 (2009). 
[13] Slangen, J. H. G., and P. Kerkhoff. "Nitrification Inhibitors in Agriculture and Horticulture: A Literature Review." Fertilizer Research (1984)