Soil erosion

Worldwide, paraquat's use brings substantial benefits to food production and sustainable agriculture; farmers remain enthusiastic about the value that it adds. In contrast to this, some groups have been very vocal in their demands for its restriction or banning and this has led to the production of a large number of reports that contain allegations regarding its safety in use.  Syngenta, the leading manufacturer, treats any expression of concern over safety very seriously and continues to work with authorizing bodies, academics and local organizations to understand and improve the safe handling of pesticides, including paraquat.  The objective of this paper in Outlooks on Pest Management is to consider the need for and benefits of paraquat alongside the issues raised by its critics and thereby to put paraquat in perspective. 
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Next time you are relaxing with a nice cup of tea, remember that this beverage once sparked a revolution. In 1773, a group protesting against unfair taxes dressed as Mohawk Indians and tipped the cargo of tea carried by ships of the British East India Company into Boston Harbor. The Boston Tea Party rallied support for the revolutionaries in the 13 Colonies and, some say, started the American War of Independence. Now, tea is a crop leading another revolution, one in sustainable agriculture.
The major environmental issues in growing tea include (Clay, 2004):
Loss of habitats and effects on biodiversity
Soil erosion on the often hilly terrain
Water pollution and reduction in soil health by agrochemicals
Deforestation as a result of the need for wood for drying tea leaves
Using the non-selective herbicide paraquat for weed control can address three of these four issues. Paraquat can be used to maintain a managed, non-competitive weed flora which provides habitats to encourage biodiversity and helps prevent soil erosion. Paraquat does not affect soil health and does not pollute soil or surface waters.
Paraquat is an essential tool in tea
Paraquat is a broad-spectrum herbicide. Its mode of action is to inhibit photosynthesis, an essential process in plants, and means that paraquat destroys all green tissue.
Paraquat and no-till methods are minimizing soil erosion and increasing productivity for corn farmers in Northern Vietnam. Corn (maize) is an important crop for the Vietnamese - especially for those living in the hilly northwest region.  180,000 hectares (ha) of corn are grown on hillside fields during the rainy season.
Traditional but time-consuming “slash and burn” farming practices limit crops to one per year and often result in low yields and high soil erosion.
Paraquat applied pre-planting and inter-row reduced soil erosion by 34% and shortened growing time by more than 20 days per season*. This represents a savings of VND **750,000 per ha in manpower costs compared to manual hand-weeding methods.
Paraquat has an important role to play in vegetable cropping because its unique characteristics are particularly suited to the challenges posed by controlling weeds in these diverse crops. Growing vegetables also helps with growing other crops in a sustainable way. Legume vegetables have bacteria associated with their roots which convert nitrogen from the air into forms which can be used by plants as nutrients and these remain in the soil to fertilize following crops. A vegetable break crop, such as peas or potatoes, prevents the build-up of pests and diseases in cereal rotations and provides an opportunity to control weeds by alternative approaches.
Using paraquat for weed control helps to address many of the challenges to vegetable production including soil erosion, leaching of agrochemicals, early harvests for best prices. Paraquat is used to prepare the land for sowing or transplanting and is safe to use for inter-row weed control in growing crops by careful application with knapsack sprayers or from tractor mounted sprayers with shielded spray nozzles. Unlike systemic herbicides which are too dangerous to use, even if small amounts of paraquat land on crop plants they cannot move within the plant to cause damage.
Vegetables fact file 70 million hectares grown worldwide
70% grown in Asia
5 portions a day recommended for health
Millions of people around the world wake-up each day with a cup of freshly brewed coffee and later meet their friends or do business in fashionably expensive coffee houses.
But for many farmers there has been a coffee crisis. Although consumption is growing in some markets, coffee is a victim of its own success, and recently there has been considerable over-supply.
In 1970 the average US consumer drank 36 gallons of coffee and 23 gallons of soft carbonated drinks. In 2000 these figures were 17 gallons and 53 gallons, respectively.
The key to success and the way out of the coffee crisis lies in quality through a sustainable approach to production. Best quality speciality coffee growers can get twice the regular price. Paraquat has a key role to play by controlling weeds that would otherwise seriously reduce productivity, in conjunction with other agronomic practices that protect the environment.
Tea is one of the leading crops in the move towards a more sustainable agriculture.
The major environmental issues in growing tea include:
Loss of habitats and effects on biodiversity
Soil erosion on the often hilly terrain
Water pollution and reduction in soil health by agrochemicals
Paraquat can be used to maintain a managed, non-competitive weed flora which provides habitats to encourage biodiversity and helps prevent soil erosion. Paraquat does not affect soil health and does not pollute soil or surface waters. 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
Paraquat only removes the top growth of well-established weeds and does not affect the germination of new seedlings.
Soybeans stand out from other major crops: broad leaved rather than a grass; a legume, so plants supply their own needs for nitrogen fertilizer while increasing the fertility of the land; and soybeans are rich in oil, protein and carbohydrate.
In the US, soybeans are grown on half of the 30 million hectares on which no-till farming is practiced. In Brazil, no-till has also been widely adopted for soybeans. Broad-spectrum herbicides, led by the introduction of paraquat in the 1960s, allowed the adoption and growth of no-till which does not rely on controlling weeds by burial from ploughing.
Soybean fact file 111 million hectares grown worldwide in 2013
90% or more of all soybean fields in USA and Argentina are GM
70% increase in productivity since 2000
40% of bean weight is oil rich in monounsaturated oleic acid
12% of US soybeans were used to make biodiesel in 2014
13 million hectares under no-till in USA
No-till systems save cash, time and fuel, improve soil structure, reduce erosion and provide havens for wildlife. Paraquat is deactivated on contact with the soil meaning that it can be sprayed to burndown weeds before planting without risking crop damage from root uptake. Paraquat works well even in cold and rainy weather.
Maize, often called corn, along with wheat and rice is one of the world’s top crops. Maize provides basic staple foods for much of the world’s population. All around the world maize grain is a basic livestock feed, and the crop can be cut while still green to make silage as a winter feed. Also, increasing amounts of maize in the US are being used to make bioethanol fuel.
Maize, perhaps more than any other crop, reaches both high and low extremes of sophistication, mechanisation and technology in crop production. But, all farmers need to maximise the yield and quality of their produce, while saving the costs, time and labor needed to grow it.
Broad-spectrum herbicides, led by the introduction of paraquat in the 1960’s, have allowed the adoption and growth of soil cultivation systems which do not rely on controlling weeds by burial from ploughing.
Global production of palm oil has now overtaken soybean oil to be the world’s leading vegetable oil. The Roundtable on Sustainable Palm Oil (RSPO) is a multi-stakeholder not-for-profit association designed to promote the growth and use of sustainable palm oil. RSPO has published a set of Principles and Criteria for Sustainable Palm Oil Production. These include that growers: Minimise erosion
Ensure the quality of surface and groundwater
Use integrated pest management (IPM) techniques to protect crops from weeds, pests and diseases
Use agrochemicals in a way that does not damage health or the environment
Soil erosion on sloping ground is especially serious. Up to 14 tonnes per hecatre of soil have been estimated as being removed every year. Plantations affected cannot be re-planted and new land must be found. “Paraquat has always given good value, with fast and effective weed control, especially of difficult weeds like ferns, woody shrubs and volunteer oil palm seedlings, even in the rainy season. These days, it is important to use paraquat to prevent weed succession problems caused by glyphosate.”
- Professor Gembira Sinuraya, North Sumatra University, Indonesia
Citrus fruit make-up a vast family including not only oranges, lemons, limes and grapefruit, but also calamondins, citrons, pomelos and ugli fruit.
Integrated pest management (IPM) systems have been introduced to minimize the impact of citrus growing on soil, water, air and biodiversity.  Paraquat has a key role in sustainable citrus production by controlling weeds that would otherwise seriously reduce productivity.  It can be used in conjunction with other techniques to manage soil erosion, particularly the use of strips of grass or legume cover crops between trees.
Paraquat can be safely sprayed to manage the weed flora along the crop rows between the grass or legume strips without fear of damaging the citrus trees.  Paraquat is immobile in soil and cannot move to the roots and up into the shoots.  Tree bark cannot be penetrated by paraquat meaning that it can be sprayed right up to the base of the trees.  Even if paraquat drifts onto citrus leaves there is little or no damage because paraquat does not move through plants like glyphosate does.
Citrus fact file 1:  Brazil is the leading citrus growing country
8.7 million ha of citrus are grown worldwide
43% are oranges, 27% mandarin types, 11% lemons and limes, 3% grapefruit
33% of crops are grown for juice