No-till

Developing no-till maize in China with paraquat

Farmers in southwest China are adopting no-till maize production using paraquat for weed control. A large proportion of crops in the region are grown by smallholder farmers on hillside fields. Soil erosion and loss of fertility are serious problems. The traditional methods of hand and mechanical weed control have very high labor demands and often cannot be done in a timely manner to achieve the best yields.

Recognizing these issues, a project was set-up to teach farmers and extension workers how to grow no-till maize. Demonstration field trials and training sessions were used to show how using paraquat in a no-till system could improve crop productivity, soil fertility and rural livelihoods.
Maize in China
While the production of rice and wheat in China has been fairly stable over the past 15 years (see chart) that of maize has increased by around 50%1. In 2009, the area of maize harvested overtook rice for the first time. Over 31 million ha of maize were harvested compared to just less than 30 million ha of rice.
One of the main reasons behind the rise of the maize crop is China’s increasing consumption of meat. Maize provides feed for poultry and livestock.

In southwest China it is common to find farmers growing three crops each year in mainly rainfed cropping systems2.

Brazil’s no-till boom fights climate change

Paraquat has always played a pivotal role in the development of no-till cropping systems in Brazil, as elsewhere. Not only has no-till helped to propel Brazil to the status of an agricultural ‘superpower’, but it has also brought many sustainable benefits by improving soils and reducing erosion, increasing biodiversity, reducing energy use and improving profitability. More recently, the contribution no-till farming can make to fighting climate change has been recognized. No-till soils sequester carbon as organic matter and because there are fewer passes over a field by machinery, considerably less fuel is used.
Brazil’s ABC Program
Plans to increase the area of no-till farming feature strongly in the Brazilian Ministry of Agriculture's ABC program (Agricultura de Baixo Carbono) launched in 2010 to target reductions in greenhouse gas emissions1. Over $1 billion worth of credit will be available to farmers to support the implementation of various approaches to reduce the impact of agriculture on climate change.

Birds benefit from no-till

Biodiversity is being encouraged by the adoption of conservation tillage practices, especially no-till farming. Spraying with a non-selective herbicide like paraquat means that weeds can be controlled without the need to plow.
Birds, in particular, are benefiting when fields are not plowed or only lightly cultivated in conservation tillage systems. Leaving stubble and chaff from the previous crop on the soil surface, and undisturbed no-till soil, provides habitats for invertebrates and small wildlife. Whether bird species feed on spilled grain and weed seeds, insects or small mammals, greater numbers are often evident.
One bird species now thriving in no-till fields in the intensive soybean growing areas to the north and south of Sao Paulo in Brazil is the burrowing owl (Athene cunicularia).
Found throughout much of North and South America, as their name implies, burrowing owls nest and roost in holes in the ground, perhaps dug by prairie dogs, for instance. During a recent ecological survey of fields in rural areas around the cities of Londrina and Uberlandia, burrowing owls and their homes were seen in many over-wintered no-till fields.
Originally a native of prairie grasslands, cultivation has meant that the birds have had to adapt to living within cropping systems.

Paraquat is glyphosate's bodyguard

A paraquat-based herbicide has become an essential land preparation tool for Brazilian farmers to stem the spread of glyphosate resistant weeds.
The extensive adoption of GM soybean varieties tolerant to glyphosate has led to farmers using this non-selective herbicide for weed control too much and too often. Although glyphosate is encouraging the continued adoption of no-till, with all the benefits to soil conservation that brings, excessive use is also encouraging glyphosate resistant weeds1. Up to three million hectares in Brazil are now estimated to be infested with five weed species which are no longer controlled by glyphosate.
However, an integrated weed control system has been developed to ensure the benefits of glyphosate can be preserved. This 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. This contains a second active ingredient, diuron. Diuron is a soil residual herbicide, but at the low rates used in this product it has little or no residual effect, but enhances the activity of paraquat.
Like paraquat, diuron works by interfering with photosynthesis, but in a different way. So-called PSII inhibitors like diuron slow photosynthesis.  (Read more about herbicide mode of action in the Knowledge Bank).

Dilemma for Brazilian farmers

Soybean growers in Brazil are facing a dilemma. More land under no-till is saving its soil and reducing energy use, but many no-till farmers are now finding that glyphosate resistant weeds are threatening future success.
No-till cropping systems have now been adopted on around 70% of cultivated land in the country, particularly for soybeans. Brazil and the US lead the world in no-till farming, but this is threatened by the rise of glyphosate resistant weeds. A recent article highlighted how worried American farmers are becoming (read more).
This is the first of two features looking at the problem in Brazil – and a success story involving a paraquat-based herbicide.
No-till and GM crops
Soybean production without soil cover is estimated to cause the loss of 55 million tonnes of topsoil in Brazil every year1. No-till cropping has been very successful in curtailing soil erosion, with its roots in the 1970s when the British company ICI began experimenting with the use of paraquat for weed control. Later, glyphosate was introduced and, with its advantage of controlling perennial weeds, has been used increasingly, year-on-year, for three decades.

No-till and biofuel crops

“America is addicted to oil” as President George W. Bush acknowledged in his 2006 State of the Union Speech. And, it is not just a US problem, nor is the addiction only to oil. Oil, coal and natural gas are the fossil reserves which power our planet, but now the spotlight is on crop biomass to provide a significant alternative source of energy and materials.
No-till farming and paraquat have a vital role to play in producing enough biomass while sustaining food production and protecting the environment.
At present, biofuels are manufactured from the parts of crops otherwise harvested for food, eg grain. This leads to two problems:

Not enough fuel
Potentially not enough food

The yield of fuel – biodiesel or bioethanol – from the oils or starch found in seeds is relatively low. With the economic and environmental motivation to grow more crops for biofuels, in future, they may take up valuable land that should be used for growing food, especially in poor Third World countries. Already, in Mexico the rising price of corn tortillas, a staple food for many poorer people, has been a problem. This has been due to the higher price of US corn, driven-up by the demand for ethanol.
To address both fuel and food issues, it would be much more attractive to use unharvested parts such as corn stover or wheat straw for biofuel production.

Integrated weed management in no-till systems

Integrated weed management and no-till are advanced agronomic tools with common aims to improve efficiency and profitabilty, while reducing the environmental impact of crop production. Although advanced in concept, these tools are straightforward and can be adapted for use in all cropping systems, from highly mechanised ones to subsistence farming, all around the world.
Tillage is a well proven means of controlling weeds, so are other methods good enough to use in an integrated approach to weed management in no-till systems? This article examines how farmers can reap the rewards of both techniques together.

Farmers around the world know just how hard it is to control weeds. They tend to come back with a vengance, especially when the many elements causing weed problems have not been appreciated and addressed. Aiming to manage weeds rather than control them is not only more realistic, but if Integrated Weed Management (IWM) is applied properly, it can reduce costs, protect the soil, and support pest and disease control.
No-till systems also provide economic and environmental advantages. However, in no-till, the traditional means of weed management by ploughing to prepare a field for cropping is not used.

Weeds and weed control

Paraquat is used to control a huge range of weeds worldwide, but to control weeds effectively and sustainably it is important to understand them.
Why does a plant become a weed? How can different types of weeds be described? What are the features of weeds and the way they grow which can be targeted by herbicides for successful control?

Paraquat and sustainable agriculture

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.

Paraquat for rice

In Asia alone, more than two billion people obtain over 60% of their calories from rice. It is the most rapidly growing source of food in Africa and is critical to food security. Long grain rices are typically of the indica race and include the fragrant Jasmine rice from Thailand and Basmati rice from India. Short grain rice, typically japonica, is usually more sticky than long grain and is favoured in Japan. Saki rice is grown in Japan to make rice wine, and in Indonesia there are red and black grained varieties. About 80% of the world's rice is grown by smallholders in these places. In Asia, women are often responsible for rice farming as men have moved to work in the cities.
Efficient and productive rice-based production systems are essential for economic development and for improved quality of life for much of the world's population. Plant breeding, crop protection, water management and fertilization have increased productivity and reduced the costs of production.
Weeds can reduce the yield and quality of rice by competing with the crop for light, nutrients and space; and their seeds can contaminate the harvested grain. Some of the most widespread and aggressive weeds are the Echinochloa species (barnyardgrass). Infestations of only ten of these weeds per square metre have been recorded to reduce yields by 25%.