Paraquat’s distinctive behaviour in soil means that farmers around the world confidently use it to protect their crops. Paraquat provides fast broad-spectrum weed control only through foliar contact action. There is no crop damage via the roots or any effect on seed germination. Soil fauna and microorganisms are not affected and there is no leaching or run-off from the degrading paraquat residues reaching the soil.
A new in-depth feature article added to the Knowledge Bank explains the fate of paraquat in soil and what the implications are for the environment and paraquat’s role in raising agricultural productivity. 
Fate of paraquat in soil Soils can deactivate paraquat equivalent to hundreds to thousands of years of application Microorganisms can quickly degrade paraquat in solution Tiny amounts of paraquat are slowly released from soil particles, degrading so that residues plateau, but not enough to have deleterious biological effects Paraquat is deactivated on contact with soil, being very strongly bound to mineral particles and organic matter
In Brazil, paraquat is helping farmers to harvest more sugarcane, more efficiently. The fast and thorough desiccation achieved by paraquat means faster harvesting, more profitable cropping and less environmental impact.
Production of sugarcane in Brazil has doubled in the past decade and is forecast to double again in the next1,2. As a biofuel feedstock sugarcane is attractive because of its high net energy gain. However, its impact on the environment and opportunities for food production are under scrutiny. Minimizing land use by increasing yield, and protecting biodiversity and the environment are important.
Leading environmental group WWF states that a major improvement in the sustainability of sugarcane crop management would be to eliminate burning the crop prior to harvest.
Benefits of paraquat harvest aid No need to burn cane
Soil organic matter increased
Biodiversity preserved
Less fuel used by harvesters
Less leaf trash in harvested cane
15+% lower transport costs
Paraquat and sustainable agriculture, by Richard H. Bromilow
In his paper “Paraquat and sustainable agriculture,” author Richard H. Bromilow studies the role paraquat plays in supporting sustainable agriculture around the world.
Abstract: Sustainable agriculture is essential for man's survival, especially given our rapidly increasing population. Expansion of agriculture into remaining areas of natural vegetation is undesirable, as this would reduce biodiversity on the planet. Maintaining or indeed improving crop yields on existing farmed land, whether on a smallholder scale or on larger farms, is thus necessary.
One of the limiting factors is often weed control; biological control of weeds is generally of limited use and mechanical control is either often difficult with machinery or very laborious by hand. Thus the use of herbicides has become very important. Minimum cultivation can also be important, as it reduces the power required to work the soil, limits erosion and helps to maintain the organic matter content of the soil.
This last aspect helps preserve both the structure of soil and its populations of organisms, and also sustains the Earth's soil as a massive sink for carbon, an important consideration in the light of global warming.
Will farming and soil quality collide?
World Agriculture and the Environment is an important new book addressing the fear that increasing demand for food and fiber is on a “collision course” with soil quality.
This article is in two parts. In Part One, some of the main issues discussed in the book are reviewed. Part Two then explains how more than 50 years of research and practical use have shown that controlling weeds with paraquat can help provide improved and sustainable crop management practices to improve soil quality.
Part One: What ‘World Agriculture and the Environment’ says
In World Agriculture and the Environment authorJason Clay (World Wildlife Fund-US vice president, Center for Conservation Innovation) reviews the production and environmental impact of 21 of the world’s major food commodities. The main threats to the environment posed by crops, fish and meat are identified and explored, as well as the trends that shape those threats.
Major Issues
Deactivation of the biological activity of paraquat in the soil environment: a review of long-term environmental fate. by Roberts TR, Dyson JS, Lane MC. In their paper Deactivation of the biological activity of paraquat in the soil environment: a review of long-term environmental fate,” the authors bring together several key environment studies on paraquat in order to analyze and assess its long-term environmental impact. They conclude that:
“These trials have demonstrated that the continued use of paraquat under GAP conditions will have no detrimental effects on either crops or soil-dwelling flora and fauna.”
Extensive long-term field studies confirm - and governments and regulatory authorities, worldwide, agree - that normal use of paraquat in accordance with the approved label instructions does not cause an unacceptable environmental impact.
These studies have shown that:
Paraquat is inactive in soil
When paraquat residues come into contact with the soil the paraquat active ingredient rapidly becomes adsorbed and strongly bound to clay and organic matter in the soil. It becomes biologically inert and as a result it cannot be taken up by plant roots or other organisms. Paraquat treated soils still maintain an active soil ecosystem with no adverse effects on soil microbes, microorganisms and earthworms. Paraquat cannot be released from the soil or re-activated by the application of water or other agrochemicals.
All agricultural soils, not only those with high clay content, have a high capacity to absorb paraquat.
Mr. Prasanna Srinivasan of New Dehli, India, is a recognized expert in the field of economics, policy and regulatory development and specializes in the impact of global environmental treaties on developing countries. Syngenta commissioned Mr. Srinivasan to provide a balanced assessment of the benefits and risks of pesticides in general and paraquat in particular. Mr. Srinivasan recently completed this review entitled, “Paraquat: A unique contributor to agriculture and sustainable development.
Please click on this link to download a copy of the review:
Paraquat: A Unique Contributor to Agriculture and Sustainable Development
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. 
Click here to download the PDF.
Paraquat product stewardship starts well before the product comes to market with thorough scientific evaluation and review of the extensive database by regulators. This stewardship has continued for more than 40 years and includes monitoring, ongoing research, scientific literature review, and regular consultation with governments, regulatory bodies, food companies, non-governmental organizations (NGOs) and farmers to ensure that their concerns are understood and addressed.
Those involved in ensuring that all approaches to crop protection are safe, effective and sustainable should visit the Stewardship Community website.
Health-monitoring studies
Stewardship efforts related to paraquat include extensive studies to assess the safety in the use of paraquat. Results of these programs have confirmed that paraquat is safe when used according to straight-forward label instructions.
A great deal is known about the likely effects of paraquat on users and hence the way to manage and avoid incidents.
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