Agriculture and Environment: Rice

Biodiversity Loss within Existing Production Areas

Many of the environmental problems from rice production result specifically from the green revolution rice production technology.

This technology has caused significant reductions in biodiversity within rice fields, particularly for paddy-grown rice.

However, it also has increased use of fertilizers and pesticides, which in turn has increased pollution of streams, rivers, and groundwater systems through runoff from fields. Rice production also generates more greenhouse gases than any other major agricultural crop.

Green revolution rice production technologies have increased production per hectare as well as the number of crops that can be grown successively each year. Clearly these production gains have reduced the habitat conversion that would have had to take place to produce as much rice using the traditional production systems prior to the development of the technology. Even so, green revolution production methods have tended to reduce quite significantly the amount of biodiversity that exists within the production system.

Traditionally, paddy fields are home to many species. Kenmore (1991) writes that "Rice ecosystems often have more than 700 animal species per hectare in highly intensified fields in the Philippines and over 1,000 so far described in Asian species of higher trophic level predators and parasitoids."

The application of ever-increasing quantities of pesticides and synthetic fertilizers, however, has led to the disappearance of much of this biodiversity, including the beneficial nitrogen-fixing algae whose absence leads to greater dependence on synthetic nitrogen fertilizers. As the agrochemicals affect the microbial life, they also affect the entire food chain that depends on them.

Paddies are no longer habitable by the dozens and dozens of species that different farmers harvested for food. In the end, the loss of water reptiles, fish, frogs, and snails deprives people of an important food source.

Current rice production is a monoculture activity undertaken in irrigated paddies. In these production systems, rice varieties are selected on the singular basis of productivity are further interbred to maximize that trait. This approach has tended to shrink the gene base, and one of the characteristics that is appearing is pest resistance, which often existed in traditional rice strains. This means that farms increasingly rely on pesticides to do what rice plants were capable of dong in the past.