NEEM TREE - THE LIVING LEGEND ! Neem is a popular Indian tree, which has gained great importance in the past couple of decades in the field of agricultureRead More....



The Neem Tree
Frequently Asked Questions
Common Names of NEEM
Neem Against Pests & Insects
Neem For Organic Farming
Neem Against Nemetodes
   
 
 

 

 

The Neem Tree (Azadirachta indica A. juss) and its derivatives have great relevance in organic farming practices. This remarkable tree has been identified as a renewable resource for home grown agro-chemicals and nutrients which are bio - degradable, non-toxic and effective.
Long before synthetic chemicals and commercial insecticides and fertilizers were available, Neem derivatives were used in Indian villages to protect and nourish crops. Scientific research has shown that Neem extracts can influence nearly 400 species of insects.
It is significant that some of these pests are resistant to pesticides, or are inherently difficult to control with conventional pesticides. (floral thrips, diamond back moth and several leaf miners). Most Neem products belong to the category of medium to broad spectrum pesticides, i.e., they are effective over a wide range of pests.
Using neem derivatives for managing pests is a non-violent approach to controlling pests. Neem products work by intervening at several stages of the insect's life. They may not kill the pest instantaneously but incapacitate it in several ways. Neem very subtly employs effects such as repellence, feeding and ovipositional deterrence, growth inhibition, mating disruption, chemo-sterilization, etc. These are now considered far more desirable than a quick knock-down in integrated pest management programs as they reduce the risk of exposing pests' natural enemies to poisoned food or starvation.
The action of Neem products fulfills all priorities among environmental objectives. This unique tree is perhaps the most significant example of how nature can combine diverse functions i.e., the action of de-oiled Neem cake as a pesticide cum fertiliser.
Chemistry of Neem for Organic Farming
Neem plants, as do all other plants, contain several thousands of chemicals. Of special interest are terpenoids that are unique to Neem and some related members of this family. More than a hundred terpenoids are known from different parts of the Neem plant. Of its biological constituents, the most active and well studied compound is Azadirachtin. However in most traditional preparations of Neem as pesticide or medicine, a mixture of Neem chemicals are present and provide the active principles. Several different kinds of azadirachtin (A-K) have been isolated, the most abundant of which is Azadirachtin-A.
The Neem terpenoids are present in almost all parts of the plant, in the living tissues. Recently, the site of synthesis and accumulation of Neem chemicals has been identified as secretory cells. Secretory cells are most abundant in the seed kernels.
 

 

 
Neem for Soil Fertility & Fertilizer Management
Good soil fertility means good crop yields. Preventing the loss of plant nutrients from an ecosystem is important for soil-fertility management. Nitrogen, phosphorus, and potassium (N,P,K) are the three major elements which determine soil fertility and should be ideally present in 4:2:1 ratio; aberrations affect fertility and therefore crop yield. Urea, containing 46% of N, is applied to crops in the largest amounts; but less than half of this N, in the form of nitrate, is available to the crops.
The rest is lost through 'leaching' or by 'volatilization', or by surface run-off after a heavy shower, (Prasad and Power 1995). Leaching of soluble nitrates into the subsoil and, eventually into ground water, is well known. Nitrate losses of 50 to 70% through leaching were observed in rice crops in India.
Leaching not only depletes precious nitrate but also takes away clay, soil, and organic matter, leading to low chemical soil fertility and low plant-available water reserves. Ammonia volatilization also can contribute to a nearly 60% nitrate loss. Loss through volatilization occurs when the denitrifying bacteria reduce the nitrate to elemental nitrogen and nitrous oxide which escape to the stratosphere and cause ozone depletion and also contribute to greenhouse warming. On the other hand, nitrate build-up in drinking water can reduce the blood's ability to transport oxygen, especially if the nitrates are converted into nitrites (blue-baby syndrome). Even ruminants are vulnerable to nitrate or nitrite poisoning, leading to poor growth rates, reduced milk production, and increased susceptibility to infections, and even abortions.
One way to minimise nitrate loss is to apply the urea more than once in smaller quantities or, alternatively, to use a slow-release urea which makes the urea available in the soil for a longer time. Bains et al. (1971) in field trials in India found that an accetone extract of neem kernel was an excellent nitrification inhibitor, even better than sulfur-coated urea. Ammonia volatilization, urea hydrolysis, and leaching, were all reduced when urea was blended or coated with neem cake.
Results from several field experiments show that neem cake coating of prilled urea increased nitrogen uptake by 4.5 to 19.4%. The increase in rice yield due to neem cake coating/blending of prilled urea ranged from 1 to 54%, the average being 9.6%. Neem cake coated urea applied to rice or sugarcane also left a carryover effect and increased sugarcane yield by 7% in the ratoon sugarcane crop .
Ready-to-use, neem-based urea-coating agents, such as 'Nimin' (containing ca. 5% neem bitter tetranortriterpenoids) are now commercially available in India. Application of Nimin-coated urea (1 part Nimin: 100 parts urea, wt/wt) reduced losses of fertiliser N through leaching and denitrification by 30-35% and increased yields in treated crops by up to 25% (Vyas et al. 1996). The bitters in Nimin delay the denitrification process up to 30 d by either killing nitrifying bacteria or suppressing their