Organic fertiliser refers to materials used as fertiliser that occur regularly in nature, usually as a by product or end product of a naturally occurring process. Organic fertilisers such as manure have been used in agriculture for thousands of years; ancient farmers did not understand the chemistry involved, but they did recognise the benefit of providing their crops with organic material.

The environmental impact of development projects is currently studied and mitigated from two distinct perspectives: before and after project implementation, with environmental impact assessment (EIA) and environmental management systems (EMS) being the main instruments on the respective sides.