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No-till Agriculture
By: *Stephen Weller and Franklin Cudjoe
The debate about how we best grow our food ‘sustain ably’ has long divided commentators. Everyone has an opinion on the serious business of how to get food to our plates. The problem is none of them seem to be able to agree.
Agriculture, the practice of growing food, is a uniquely human activity. It is an integral part of our success as a species. Our ability to use technologies to feed a growing world population is vital to our survival. Perhaps this is why the type of technology used is such an emotive and divisive subject.
While the debate about technology goes on amongst various schools of thought, a quiet revolution has been taking place, little heard of and little understood. Agriculture’s best-kept technological secret is simple - stop using the plough.
It sounds too good to be true, and too absurd to be serious. However, the practice of no-till farming, essentially not ploughing or tilling the soil, is catching on and delivering benefits in almost every critical aspect of agriculture. Conservation Agriculture as it has become known, improves nutrient deficiencies in the soil, improves water efficiency, controls erosion, addresses soil structure deficiencies, improves pest management, reduces environmental degradation and limits the loss of biodiversity and wildlife habitats.
At last, something everyone can agree on. Alas, not so, for this seemingly utopian farming method involves the use of one essentially benign chemical technology at the expense of a destructive, traditional, mechanical technology.
The problem with traditional farming is that it normally involves intensive ploughing, or tillage, of the soil as the main starting point. This practice removes weeds to prepare the seedbeds and was also thought to improve the soil’s fertility. However, in the long term over-ploughing reduces the soil’s organic matter and exposes it to wind and water erosion. According to the US Environment Protection Agency sedimentation due to wind and water erosion is the most important pollutant affecting water quality. High levels of sediment in waterways destroys habitat, increases the need for water treatment and dredging and decreases the storage capacity of reservoirs. Conservation Agriculture can reduce water runoff by up to 70% and sedimentation into surface water streams by around 90%.
It wasn’t until the introduction of a piece of technology known as ‘broad spectrum herbicides’ that Conservation Agriculture could really take off and become a viable agricultural approach. These environmentally benign herbicides are used to clear weeds instead of ploughing. The seed is sown directly into the previous season’s stubble with little or no ploughing. Ground cover or mulch is encouraged, essentially leaving dead plant matter on the field, which prevents erosion, as well as trapping in moisture and nutrients. The use of herbicides allows this because the soil does not have to be turned over to kill the weeds.
This practice also improves soil biodiversity such as bacteria, insects and fungi. This abundance of organisms in the soil helps the mulch to decompose into humus, helping to stabilize the soil structure and increase its fertility. According to research from Argentina, where conservation agriculture is practiced on over 9 million hectares, maintaining mulch on the fields is estimated to increase the soil’s organic matter by about 1% every ten years.
It is not all simple though. As with organic farming there are risks when changing over from conventional farming. Pest and disease control requires special attention as does weed management. Weeds compete with crops for nutrients, moisture, sunlight and space and too many can result in significant crop losses. Losses of 50 to 90% are not uncommon for crops grown in natural weed infestations.
Conservation Agriculture is not a niche practice carried out by a few fanatics trying to prove a point. The research has been going on since the 60’s and it is being commercially practiced on nearly 60 million hectares around the world including the USA, Brazil, Argentina, Australia, Canada, India, Pakistan, Malaysia, Chile, Colombia, Mexico, Uruguay, Paraguay, Bolivia, Venezuela and Ghana.
However, there is still a long way to go and trying to convince a farmer not to plough his field, a practice handed down to him by his forefathers, is a struggle. Research into no-till agriculture in West Africa began as early as the 1960s, but it wasn’t until the various interested parties formed a partnership approach in the 1990’s that conservation agriculture began to be appreciated and adopted.
In Ghana maize farmers were convinced by a program of on-farm demonstrations outlining an entire farm management system. This included the use of certified seed, organic and inorganic fertilizer, pre- and post-planting weed control and harvesting techniques that left crop residues in the field. These demonstrations were supported by pre-season farmer training, field days, field tours, workshops and printed guides.
The no-till approach in Ghana has increased yields in both normal and dryer years due to better land management and more moisture in the soil. Between the early 90’s and 2000 it is estimated that more than 100,000 farmers have adopted conservation tillage methods on about 45,000 hectares of maize and grain legumes.
Another of the attractions of conservation agriculture, and why it is being adopted so widely, is that it is effective for small, medium and large scale farming operations. The subsistence farmer to the industrial farmer can all benefit along with the environment.
Some questions linger on the ability of no-till to allow aeration and infiltration needed to circulate plant nutrients for deep-rooted crops. Perhaps some amount of tillage would be required here. In temperate regions, the approach could affect crops when temperatures run low.
Again since shifts in weed populations are likely and apart from careful selection of herbicides, which requires more extensive information, the other way to go around it will be crop rotation. But the approach is more likely to succeed with monocrop culture as crops have differing nutrient intake capacities.
They key to the quiet success of conservation agriculture, and possibly one of the reasons it rarely hits the headlines, is that it does not polarize the issues. It uses a blend of techniques and technologies without prejudice. The only criteria are to be effective. Let us hope that those interested in agriculture can put their ideological differences aside, look at the facts and put their undoubted energies into promoting an approach that works for people and the planet.
*Stephen Weller is Director of Communications for the International Policy Network (IPN) in London. Franklin Cudjoe is Director of Imani: The Centre for Humane Education in Ghana and a Fellow of IPN.
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IMANI Center for Policy& Education