Paraquat for tea
Tea is one of the leading crops in the move towards a more sustainable agricultureParaquat only removes the top growth of well-established weeds and does not affect the germination of new seedlings. This maintains the balance of the weed flora and prevents shifts to noxious species simply because bare ground is less available for them to colonize. The presence of non-competitive vegetative cover helps to stabilise the soil, resisting erosion, and also provides habitats to encourage biodiversity. The wildlife encouraged will include predators of insect pests, which would otherwise have to be controlled chemically. Paraquat’s unique combination of biological and physico-chemical properties, particularly its non-systemic action and extremely strong soil adsorption, give it a very robust environmental profile. When paraquat makes contact with soil, it is immediately very tightly bound to soil particles, making it both immobile and inactive. Paraquat can be safely sprayed between the crop rows without fear of damaging the tea plants. It cannot move to the roots and up into the shoots. Bark cannot be penetrated by paraquat meaning that it can be sprayed right up to the base of the bushes. Soils are capable of adsorbing vast quantities of paraquat. Clay content is important, but even for lighter soils the adsorption capacity in the top few centimetres is capable of deactivating many kilograms of paraquat per hectare. Tiny amounts of paraquat are continuously released from clay into soil water. There, soil microbes degrade it to carbon dioxide, ammonia and water, preventing soil accumulation. Paraquat cannot leach
DescriptionManagement and conservation of the natural resource base and the use of technological and organizational change in a manner that ensures continued agricultural production from the land for present and future generations. Such practices conserve land, water, and plant and animal genetic resources. They are environmentally non-degrading, technically appropriate, economically viable, and socially acceptable. Sustainability rests on the principle that we must meet the needs of the present without compromising the ability of future generations to meet their own needs. Therefore, stewardship of both natural and human resources is of prime importance.
Authoritative On-line References and Resourceswww.nal.usda.gov Information from the USDA's Alternative Agricultural Systems Information Center.. The major environmental issues in growing tea include:
- Loss of habitats and effects on biodiversity
DescriptionThe variety of life in all its forms, levels and combinations. Includes ecosystem diversity, species diversity, and genetic diversity (IUCN, UNEP and WWF, 1991).
Authoritative On-line References and Resourceshttp://earthtrends.wri.org/ EarthTrends is a comprehensive online database, maintained by the World Resources Institute, that focuses on environmental, social, and economic trends. Statistics on biodiversity indicators are available.
- Soil erosion
DescriptionDisplacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement.
Authoritative On-line References and Resourceshttp://soilerosion.net/ This site brings together reliable information on soil erosion from a wide range of disciplines and sources. It aims to be the definitive internet source for those wishing to find out more about soil loss and soil conservation. on the often hilly terrain
- Water pollution and reduction in soil health by agrochemicals
The Tea Research Institute of Sri Lanka recommends using paraquat as a weed management solution allowing reduced use of glyphosate, stating: “Manual weeding and chemical weeding with paraquat in rotation could be advocated to sustain productivity and maintain an eco-friendly environment in tea plantations.”
Tea fact file
- 3.5 million ha grown worldwide, mainly in Asia
- 133%: increase in area harvested in Vietnam, one of the top five producing countries, since 1995
- 75 tonnes/ha of soil eroded annually from hilly tea estates in Sri Lanka
- 3 main varieties: Assam, China, Cambodian