Conservation tillage

US crop scientists are excited about the potential to protect soil in fields where corn is grown for biofuel production by the use of perennial cover crops suppressed by paraquat.
In the near future, the food versus fuel dilemma will be addressed by using ‘waste’ crop residues instead of grain as the feedstock for bioethanol. However, the concern is that removal of stover and chaff normally returned to the soil will cause serious erosion and fertility problems.
Iowa State University has conducted a three-year project that has demonstrated how carefully managed perennial cover crops can more than substitute for the biomass harvested for ethanol production1. The key to success is the use of paraquat and its fast, contact-only action. Paraquat is used to burn down the cover crop in spring, but because it is not translocated and is adsorbed by soil, the cover crop recovers to protect soil after harvest and over winter.
Second generation biofuels
The UN Food and Agriculture Organisation (FAO) has begun to implement its strategy for Sustainable Crop Production Intensification (SCPI). By 2050, FAO estimates that to feed each person on the planet there will only be 0.16 ha of agricultural land available, compared 0.26 ha in 1999 and 0.4 ha in 1960, hence the need to intensify production. The goal of SCPI is to support countries and their farmers to grow more food and the focus will be on developing technologies and policies that will ensure sustainability1,2.
Conservation Agriculture
In practice, this will be achieved by encouraging the global development of the approach to farming known as Conservation Agriculture. This is quickly gaining ground as the best means of securing a stable and sustainable food supply for the world’s population of 9 billion estimated for 2050.
Conservation Agriculture integrates the best appropriate technologies to work within three main pillars which support the overall concept. These all acknowledge the importance of creating and maintaining a healthy soil. Integrating diverse approaches to the management of weeds, pests and diseases, as well as plant nutrients, is also essential.
Three pillars of Conservation Agriculture Minimal soil disturbance: not plowing and ideally no soil cultivations, eg ‘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.
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. Plowing, even though it effectively removes weeds by burial, is costly, time consuming, and can cause soil erosion and compaction.
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.
Paraquat, used in a conservation tillage system, has reaped rewards for two Virginia cotton growers. Brothers Cliff and Clarke Fox of Foxhill Farms have been named Farm Press High Cotton Award winners for the Southeast region.
The Fox brothers planted their first crop of cotton in 1994, using traditional tilling methods. They began the switch to conservation tillage with their second crop. Today, their conservation tillage approach is firmly established.
As reported in a January 5, 2006 article in the SouthEast Farms Press, for their award-winning crop, the brothers “use a burn down herbicide, either glyphosate or paraquat, depending on the weed history of the field and time of application.”
Low- or no-till farming benefits land by helping to reduce soil erosion and conserving soil moisture. Paraquat contributes significantly to conservation tillage systems - such as those used by Foxhill Farms - by controlling weeds with its fast, contact-only action, which kills weeds while leaving root structures intact.
Congratulations to Cliff and Clarke Fox of Foxhill Farms. View the complete story on the SouthEast Farms Press website:
For more information about the benefits of paraquat in sustainable agriculture, click here.
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