Sometimes sewage sludge is used, which may contain pathogens and other contaminants. Finally, some areas in tropical countries may have such low soil fertility that synthetic inputs are necessary. Integrating trees and shrubs into the farm system also conserves soil and water and provides a defense against unfavourable weather conditions such as winds, droughts, and floods. Techniques used in organic agriculture also reduce water pollution and help conserve water on the farm. A few developed countries subsidize or compel farmers to undertake organic production as a solution to water quality problems.
Organic agriculture requires a diversity of crops and livestock.
This contributes to whole farm health, provides conservation of important genotypes, and creates habitats for beneficial species. Standards are, therefore, expected to reflect local conditions so that pollution is minimized. For example, restrictions on the number of livestock or amount of manure to be used per unit of land are not exceptional. However, it has been argued that, at present, these are areas of peripheral attention, as compared to the scientific aspects of the management system. This can only be achieved through farmer's participation in research and its application.