Conservation tillage

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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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
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.
Cotton is a fibre which protects the seed of the cotton plant, much as the flesh of an apple protects the pips.
In 1997, GM cotton tolerant to the non-selective herbicide glyphosate was introduced. Although herbicide tolerant cotton has many advantages, it has contributed to enormous increases in the use of glyphosate which is now posing problems by encouraging the development of resistant weeds which are no longer controlled by this herbicide.
No more than two applications of glyphosate should be applied to any one field over two seasons. Paraquat can provide the alternative means of effective and sustainable weed control.
Using paraquat in weed control programmes can also address a number of environmental issues concerned with cotton growing including soil erosion and degradation, water contamination by run-off and leaching of agrochemicals, and loss of habitats and effects on biodiversity.
Paraquat is deactivated on contact with the soil meaning that it can be sprayed to burndown weeds before planting a cotton crop without risking damage to that crop or indeed subsequent crops in the rotation. It does not pollute soil or surface waters because it is immobilised and deactivated immediately on contact with soil.
In this section you will find articles about paraquat's environmental profile. One of paraquat's key chemical properties, fundamental to the way it is used in sustainable farming systems, is that it is inactivated immediately on contact with soil.
Paraquat has been an essential tool for farmers in protecting sustainable cropping systems for more than 50 years. Its unique properties have enabled the development of vital new crop production techniques, especially no-till.
This section includes in-depth features that cover topics including:
Paraquat's role in sustainable agriculture
All about weeds and weed control
Important crops and their production systems
Paraquat led to a revolution in land preparation that has had profound economic, social and agronomic effects around the world.
The herbicidal properties of paraquat were discovered by ICI (a legacy company of Syngenta) in 1955 and was introduced to world markets in 1962 under the brand name GRAMOXONE®. Paraquat quickly gained acceptance as a tool for controlling weeds in emerged row crops and tree crops. However, it was the realization that paraquat could replace time- and labor-intensive plowing, which in the 1960s and 1970s led to an expansion of research around the world on a scale unprecedented for a single agricultural chemical and to a revolution in farming.
Why is paraquat such an unique product and why is it so valuable to farmers? Before we can answer that we have to consider the importance of weeds.
Weeds have existed as long as man has farmed. Weeds hinder planting a crop and once the crop has emerged they continue to compete for water, light, nutrients and space. Weeds need to be removed before planting and controlled thereafter.   There are several ways to control weeds:
Hand Weeding is hard, debilitating and tedious work. It can occupy the farmer and his family for many hours of the day.  In many parts of the world hand weeding is the most time-consuming human activity aside from sleeping.
Reduces soil erosion
By killing weeds but leaving roots in place, paraquat stabilizes the soil.
Case Study
In the five year Sagip-Lupa project in the Philippines researchers have been collaborating to study approaches to reducing the serious threat to food production and the environment. posed by soil erosion
On the three experimental sites an average of more than 100 tonnes/ha of topsoil has been lost each year by farming in the traditional way. The large savings of precious topsoil from using paraquat and no-till are all statistically significant.
Crop yields have also benefited.
Read more …
Increases soil organic matter
Using paraquat in conjunction with less soil tillage helps to preserve organic matter. This is good for soil health and structure, increasing fertility, improving water infiltration and retention, and locking up carbon dioxide.
Case Study
No-till crop production using paraquat for weed control is enabling the successful cultivation of one of China’s last available soil resources for food production.
In Southern China nearly 30 million hectares of red soils have been cultivated, but they are highly weathered, inherently infertile and very susceptible to erosion. Paraquat and no-till can help by stabilizing the soil.
Controls weeds
Paraquat is an important tool for weed management. It controls many species and can be used with most crops. Its mode of action means that it is especially valuable where intensive use of glyphosate has caused, or threatens to cause, the development of glyphosate resistant weeds.
Case Study
The extensive adoption of glyphosate tolerant GM crops has led to farmers over-relying on glyphosate.
Although glyphosate is encouraging the continued adoption of no-till, with all the benefits to soil conservation that brings, up to three million hectares in Brazil are now estimated to be infested with glyphosate resistant weeds.
However, an integrated weed control system involves continuing to spray glyphosate for burndown, but following just before or just after planting the crop with an application of a paraquat-based herbicide.
Read more …
Acts fast
Paraquat acts fast in all seasons, no matter what the conditions: hot, dry, wet, early season or late. Paraquat is rainfast in 15 - 30 minutes.
Case Study
In West Bengal, India, using paraquat to burndown weeds in a no-till system means farmers can transplant a new rice crop after only four days compared to the usual 12 days. Traditionally, fields are plowed and farmers have to wait for buried weeds to decompose sufficiently to allow a final cultivation.