How weeds can be controlled in organic farming?

Organic farms use manual weeding, water management, tillage, mulching, crop rotation for weed suppression etc as some of the cultural ways of weed management. It is believed that weeds on the organic farm improve soil condition, provide habitat for natural enemies, helps in soil conservation etc. Mulching the soil basin with plastic material is permitted on organic farms only if they are removed at the end of the cropping season. The use of natural substances is permitted but their efficiency of the weed removal process is not yet clear.