|Case Studies of Neem Processing Projects Assisted by GTZ in Kenya, Dominican Republic, Thailand and Nicaragua (GTZ, 2000, 152 p.)|
|2. Survey of neem-processing methods|
To prepare a simple extract from 1 kg of crushed neem seed or fruits, these are soaked and stirred in 20 litres of water and left for 5 to 8 hours, preferably during the daytime (Dreyer & Hellpap 1992, Hellpap 1989, Schmutterer 1995). The neem extract can be filtered and directly sprayed on the target crops, preferably in the evening to avoid UV light (which destroys the active ingredients) as long as possible.
This method is also known as the "tea bag method".
There are some examples reported from Thailand, where this method is even used for larger areas of vegetables. Farmers have developed simple technologies, putting 50 kg bags of crushed neem fruits into iron drums and spraying the water extracts on a large scale with motor driven pumps.
The neem remains or marc can be dried and packed or applied to the soil as a soil additive or to control soil insect pests and nematodes.
In addition, the neem seeds or neem cake from oil pressing may be ground to produce powder. This powder can be used to produce water extracts or can be directly applied to the soil or to plants themselves (e.g. funnels of maize).
Neem seeds can also be processed into oil which, mixed with soap (or better, an emulsifier) can be applied by spraying.