neem oil

Use as a fertilizer
Neem oil organic manure protects plant roots from nematodes, soil grubs and white ants probably due to its residual limonoid content. It also acts as a natural fertilizer with pesticidal properties. Neem cake is widely used in India to fertilize paddy, cotton and sugarcane. Usage of neem cake have shown an increase in the dry matter in Tectona grandis (Teak), Acacia nilotica (Gum Arabic), and other forest trees.
Neem seed oil also reduce alkalinity in soil, as it produces organic acids on decomposition. Being totally natural, it is compatible with soil microbes, improves and rhizosphere microflora and hence ensures fertility of the soil. Neem oil improves the organic matter content of the soil, helping improve soil texture, water holding capacity, and soil aeration for better root development

Pest control
Neem oil is effective in the management of insects and pests. The bitter principles of the soil and cake have been reported to have seven types of activities (a) antifeedant (b) attractant (c) repellent (d) insecticide (e) nematicide (f) growth disruptor and (g) antimicrobial.
The oil contains salannin, nimbin, azadirachtin and azadiradione as the major components. Of these, azadirachtin and meliantriol are used as locust antifeedants while salannin is used as an antifeedant for the housefly.

Components
Neem oil has an adequate quantity of NPK in organic form for plant growth. Being a totally botanical product it contains 100% natural NPK content and other essential micro nutrients as N(Nitrogen 2.0% to 5.0%), P(Phosphorus 0.5% to 1.0%), K(Potassium 1.0% to 2.0%), Ca(Calcium 0.5% to 3.0%), Mg(Magnesium 0.3% to 1.0%), S(Sulphur 0.2% to 3.0%), Zn(Zinc 15 ppm to 60 ppm), Cu(Copper 4 ppm to 20 ppm), Fe (Iron 500 ppm to 1200 ppm), Mn (Manganese 20 ppm to 60 ppm). It is rich in both sulphur compounds and bitter limonoids.
According to research calculations, neem oil seems to make soil more fertile due to an ingredient that blocks soil bacteria from converting nitrogenous compounds into nitrogen gas. It is a nitrification inhibitor and prolongs the availability of nitrogen to both short duration and long duration crops....