Milestones on the road to sustainable farming

It takes skill to no-tillDescription Also known as conservation tillage or zero tillage is a way of growing crops from year to year without disturbing the soil through tillage ie cultivating the soil usually with tractor-drawn implements. Authoritative On-line References and Resources http://www.no-till.com/index.htm A portal for on-line information about no-till farming., but persevering and wider adoption could bring many benefits, says an article on ‘No-Till: the Quiet Revolution’ in a recent edition of Scientific American. 

No-till is a way of growing crops without plowing. The authors, soil and sustainable farmingDescription Management and conservation of the natural resource base and the use of technological and organizational change in a manner that ensures continued agricultural production from the land for present and future generations. Such practices conserve land, water, and plant and animal genetic resources. They are environmentally non-degrading, technically appropriate, economically viable, and socially acceptable. Sustainability rests on the principle that we must meet the needs of the present without compromising the ability of future generations to meet their own needs. Therefore, stewardship of both natural and human resources is of prime importance. Authoritative On-line References and Resources www.nal.usda.gov Information from the USDA's Alternative Agricultural Systems Information Center. experts David Huggins, USDA, and Prof. John Reganold (Washington State University) cite the introduction of paraquat as a milestone in agriculture which made no-till possible.

As a broad spectrum, 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. herbicide, paraquat controls weeds without the need to bury them by ploughing. The problem with ploughing is that it causes soil erosionDescription Displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement. Authoritative On-line References and Resources http://soilerosion.net/ This site brings together reliable information on soil erosion from a wide range of disciplines and sources. It aims to be the definitive internet source for those wishing to find out more about soil loss and soil conservation.. Thanks to John Deere’s adaptation of the mouldboard plow in 1837 the North American prairies could then be cultivated. However, as cropping continued to expand and intensify, problems became all too obvious. Take the Palouse region in Washington State. By the 1970s, all topsoil had been totally eroded from 10% of the cropland and up to 75% had been lost from another 60% of fields.

Another US soil scientist, David Montgomery, reckons that it takes on average around 1000 years to form one inch (2.5 cm) of soil. Montgomery has noted that the duration of ancient civilisations has been linked to soil. The plow’s advantage as it evolved through better design and more pulling power over thousands of years was that it enabled more and more land to be cultivated, growing crops for more people with less manpower. However, long lasting civilisations have been located where soil is more quickly replenished by alluvial deposition, eg along the Nile. Otherwise, soil erosion has meant that agriculture has not been sustainable.

Our civilisation is now at the limits of cultivatable land if the wild places and lungs of the planet are to be preserved and a different approach is needed. In no-till, weeds are removed by a broad spectrum herbicide and then a no-till seeder drills seed in rows of very narrow shallowly cultivated strips, leaving most of the soil untouched. Controlling weeds with paraquat which is inactivated and immobilised on contact with soil, and using today’s advanced no-till seeders enables large areas to be cultivated quickly without plowing and to care for the environment.

When the benefits of no-till are listed it is hard to see why barely 7% of the planet’s crop land is cultivated by no-till practices (Fig. 1). No-till reduces soil erosion, conserves water, improves soil health, reduces fuel and labor costs, reduces sediment and fertilizer pollution of lakes and rivers and sequesters carbon.

The problem with no-till is that it is often hard to get started. Specialist planting machinery is needed which is often expensive; germination and crop establishment can be slow; and patience is required to built-up the ultimate improvements in soil structure. Herbicides must be used carefully to avoid resistant weeds or more aggressive ones becoming a problem. Varying the mode of action of herbicides helps to keep resistance at bay. Paraquat can be used in conjunction with glyphosate to avoid the development of glyphosate resistant weeds which have become an issue with the huge use of glyphosate in GM crops. Paraquat is much faster acting and more rainfast than glyphosate, so is ideal for a rapid burndown of weeds before planting. Unlike residual herbicides which are used to control weeds before they have emerged, paraquat is a contact herbicide which is used to control weeds only when they are present and posing a problem. Glyphosate can then be used for selective weed control in glyphosate tolerant crops like soybeans, cotton and corn, with less risk of weeds becoming resistant.

No-till is, in fact, just part of an approach to sustainable crop production called 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.. The main principle behind conservation tillage is that the soil should be protected by vegetative cover for as long as possible – at least 30% covered after planting, officially in the US. On some farms and soils, following a conservation approach to cultivations is an easier way to abandon plowing than going into the ultimate no-till system straight away. Leaving straw and stubble over the field after harvest, allowing some controlled growth of weeds, or growing a cover cropDescription 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. over winter, markedly reduce soil erosion. No-till systems have been recorded as decreasing soil erosion by up to 98% depending on crop, soil-type and terrain. They also restrict 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. and improve infiltration which is increasingly important in droughted areas.

Wildlife above and below ground also benefits from the cover. Birds and beneficial insects enjoy the food and habitat provided by the continual soil cover and earthworms and other soil animals and insects thrive on the greater soil organic matter levels and better structure with less compaction.

Both systems are gaining in popularity amongst US farmers (Fig. 2). The greater amounts of soil organic matter which accumulate with no-till take large amounts of carbon dioxide out of the atmosphere. The most recent boost to no-till has been the setting up of carbon trading schemes whereby no-till farmers can sell credits for each acre no-tilled.

There are 525 million farms in the world. Eighty-five percent are less than 2 ha (5 acres) and 95% are in Asia (87%) and Africa (8%). Yet, as seen in Fig 1, the uptake of no-till in these parts of the world is very low. Apart from the environmental benefits of no-till or conservation tillage, the 50-80% reductions in fuel use and 30-50% reductions in labor requirements would be especially welcome there. In addition to controlling weeds before planting, paraquat can be used to control weeds emerging later in crops such as corn and vegetables grown in wide rows. This provides a very simple system, freeing farmers, their wives and children from the drudgery of hand-weeding, allowing more time for growing more crops or other enterprises and education.

Paraquat and no-till are helping farmers towards a sustainable agriculture – protecting the soil, making money and giving a better quality of life, all in the course of feeding people.

Reference

Huggins D R & Reganold J P. No-Till: the Quiet Revolution.
Scientific American, July 2008, pp 70-77.
http://www.sciam.com/article.cfm?id=no-till