Conservation tillage earns carbon credits

By providing the non-selectiveDescription A chemical product used for eliminating all types of weeds (annual and perennial grasses and broadleaved weeds). Authoritative On-line References and Resources http://www.weeds.iastate.edu/ An invaluable source of contemporary information about herbicides and weeds from Iowa State University. weed control essential in conservation tillageDescription Any tillage and planting system that covers 30 percent or more of the soil surface with crop residue after planting to reduce soil erosion by water. Authoritative On-line References and Resources http://www2.ctic.purdue.edu/Core4/CT/Definitions.html Core4Conservation is part of the Purdue University-based Conservation Tillage Information Centre. systems, paraquat is helping to mitigate climate change.

US farmers can now enrol in the Farmers Union Carbon Credit Program which means they will get paid for managing their cropland using conservation tillage systems like no-till and strip-till. Conservation tillage increases the amount of organic matter in the soil, and apart from being good agricultural practiceDescription Refers to the package of recommendations and available knowledge to address environmental, economic, and social sustainability for on-farm production and post-production processes resulting in safe and healthy food and non-food agricultural products. GAP may consist of guidelines addressing issues of site selection, adjacent land use, fertilizer use, water sourcing and use, pest control and pesticide monitoring, harvesting practices (including worker hygiene, packaging, storage, field sanitation, and product transportation), and cooler operations. Authoritative On-line References and Resources http://www.fao.org/prods/GAP/index_en.htm The UN FAO provides independent information on GAP programmes, practices and standards., this sequesters large amounts of carbon dioxide.

Agricultural land has the potential to offset about 11% of US greenhouse gas emissions, equating to some 650 million tonnes of CO₂ every year. Of this total, cropland could contribute 41% and half of this could be met by conservation tillage practices being adopted more widely. President of the Soil Science Society of America, Professor Rattan Lal (Ohio State University), has described this as a “win-win-win strategy, because it mitigates climate change, improves productivity and enhances ecosystems”.

Recently, the Soil Science Society of America published a series of articles about how conservation tillage can make a major contribution to carbon sequestration and how farmers can benefit from this by enrolling in carbon trading schemes (https://www.soils.org/sciencepolicy/caucus/briefings/carbon/).

Here’s how it works, how paraquat can help, and how we all benefit …

No-till on M&K Farms, Kansas

Merle Holle has grown corn, wheat, grain sorghum and soybeans in north-east Kansas for fifty years. Now farming with his son on M&K Farms at Marysville, these no-till enthusiasts have practised the technique since 1990. Moving away from clean seedbeds on plowed fields was an act of faith, until the benefits became all too obvious, and after five years getting familiar with no-till and its results, M&K Farms never looked back. Under no-till, soil structure improved, with no capping or compaction and much less erosion. There was less water run-offDescription The occurrence of surplus liquid (like rain) which originates up-slope and is collected beyond the ability of the soil to absorb it. The surplus liquid then flows away over the surface to reach the nearest surface water (pond, lake, river). Authoritative On-line References and Resources http://www.sowap.org/index.htm SOWAP (Soil and Water Protection) is a collaboration between industry, NGOs, universities and farmers to test a range of site-specific soil management methods, based on the concept of conservation tillage. It has looked at economic and environment aspects including effects on soil erosion and run-off., better habitats for wildlife and crop stands were better. What was also clear to the Holles was that even if they did need a little more herbicide, they were saving on fuel, machinery and labour costs, and putting more than $20/acre back in their pockets.

Less obvious was that considerably less CO₂ was going into the atmosphere from the Holles’ fields. The better soil structure from no-till is due to more organic matter which means that carbon is effectively sequestered, so reducing greenhouse gas emissions. Since the 2005 season, M&K Farms have entered into a contract with the Chicago Climate Exchange (CCX) whereby they get paid for every no-tilled acre. The idea is that organisations which either need to reduce their greenhouse gas emissions to comply with the Kyoto Protocol, or wish to do so through good corporate citizenship, may find it easier to pay someone else to reduce emissions on their behalf. This is carbon trading and American farmers who adopt certain conservation tillage practices can earn CCX Exchange Soil Offsets as carbon credits. Farmers can take out contracts through pooled schemes such as that run by the Farmers Union (http://carboncredit.ndfu.org/).

Eligibility for Carbon Trading

CCX Exchange Soil Offsets are currently available across most of central and eastern USA in seven zones designated by the typical ability of their soils to store carbon if no-till or strip-till practices are adopted. As a general rule at least two-thirds of the soil surface must remain undisturbed with at least two-thirds of crop trash left over the surface. Mouldboard plows, discs and chisel plows are not allowed to be used and cover cropsDescription Cover crops are primarily planted not to be harvested for food but to reduce soil erosion, control weeds and improve soil quality. They are usually plowed or tilled under before the next food crop is planted, in which cases the "cover crop" is used as a soil amendment and is synonymous with "green manure crop." Authoritative On-line References and Resources http://attra.ncat.org/attra-pub/covercrop.html ATTRA is the US National Centre for Appropriate Technology's Sustainable Agriculture Information Centre. must be planted if continuous soybeans, cotton or pulses are grown.

Farmers in each zone are paid a rate according to the carbon sequestration potential of their soils. Sequestration rates of 0.2 – 0.6 tonnes of carbon per acre are credited for each year of contracts which currently run until 2010. There are random spot checks on compliance on participating farms, but no measurements of organic matter are made. This made earlier schemes far too expensive to administer. The price of carbon on the Chicago Climate Exchange varies every day with trading, but in the first half of 2007 was $3.50 - $4.00 per tonne.

Role of Paraquat

As the first non-selective broad spectrum herbicide to become available to farmers, paraquat allowed the development of no-till conservation tillage systems. Plowing and other tillage operations control weeds which shade crops and compete for water and nutrients so reducing yield and making harvesting difficult. Plowing encourages the degradation of organic matter and in doing so CO₂ is returned to the atmosphere. The benefits M&K Farms have found from no-till with chemical weed control are typical.

Although the systemic non-selective herbicide glyphosate is often used in no-till, paraquat has many advantages, including much faster speed of action and rainfastness. Using paraquat as the burndown herbicide means that glyphosate can be sprayed post-emergence in tolerant GM crops with less fear of weed resistanceDescription The inherited ability of a plant/weed to survive a dose of a herbicide normally lethal to that species. Authoritative On-line References and Resources http://www.weedscience.org/in.asp The International Survey of Herbicide Resistant Weeds monitors the evolution of resistant species and assesses their impact. All confirmed instances of new cases are listed. to glyphosate developing.

Paraquat, unlike glyphosate, is not systemic and only kills sprayed leaf tissue. Roots remain intact and help to anchor the soil, resisting erosion. Paraquat is also not residual, so seeds in the soil are unaffected and may germinate to provide more ground cover. The crop will out-grow any new flushes of germination, but non-competitive new weed growth will also contribute to carbon sequestration when it is ultimately added to soil organic matter along with crop remains after harvest.

Read about paraquat’s mode of action here.