In many parts of the world soil tillage and the preparation of a fine seedbed are still considered characteristics of good farming practice. With the development and refining of the mouldboard plough in recent centuries in temperate areas, and the contribution of the plough to increasing agricultural production during that time, the plough has become a symbol of progressive agriculture.

The introduction of the plough to fragile tropical ecosystems, however, and the introduction of motorised tractor power and the soil tillage concepts associated with it, have become a major threat to the sustainability of agricultural production. The development of different crop production methods in various climatic zones of the world has, over the last decades, shown that the production of crops without ploughing and even without any form of mechanized tillage is not only possible but economically feasible. These methods have come to be collectively known as conservation tillage, common results of which include reduced loss of soil, organic matter, nutrients and water as well as lower input costs of energy, time and labour relative to conventional tillage.

These Proceedings present the results of a workshop on conservation tillage held in Harare, Zimbabwe, 22 - 27 June 1998, and convened by the Food and Agriculture Organization of the United Nations (FAO), the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ), the Agricultural Research Council of South Africa (ARC), the FAO/SIDA Farm-Level Applied Methods for East and Southern Africa (FARMESA) and the Zimbabwean Farmers Union (ZFU).

The objectives of the workshop were

• to promote the concept of conservation tillage;
• to prepare the outline of a regional project leading to first steps for a possible regional action plan in support of conservation tillage methods in Africa; and
• to formulate the first draft of an international code of conduct on soil management.

The invited papers provide a useful inventory of technologies and approaches existing in different regions and countries; an overview of factors of success and failure of spreading conservation tillage and a list of possible options for successful dissemination of conservation tillage.

In addition, however, the Proceedings contain a useful compilation of advice, experience and opinion on

• the importance of conservation tillage for sustainable agriculture;
• the technologies available;
• the dissemination of information on conservation tillage; and
• the socio-economic and institutional frameworks required for conservation tillage adoption.

The most desirable form of conservation tillage leaves a protective blanket of leaves, stems and stalks from previous crops on the soil surface. This shields the soil from sun, wind and rain, thereby reducing temperature fluctuations and moisture loss, and increasing moisture penetration and biological activity. Reduced tillage also means lower fuel and labour costs.

The Proceedings pose as many questions as they answer, which in itself reflects the diversity of viewpoints on conservation tillage. Important questions that remain unresolved include

• how to practice conservation tillage in semi-arid areas with little or no crop residues due to low biomass production, communal grazing systems, excessive livestock, poor soils, minimal rainfall and/or subsistence economies;
• the role of commercial inputs such as herbicides;
• the need for better linkages among farmers, extensionists and researchers;
• the participation of women in technology development and dissemination;
• how to gain political support for conservation tillage;
• who should fund technology development: government, industry or farmers;
• how to address issues such as land tenure, user rights, and grazing rights.

The Proceedings emphasise the need for multi-disciplinary development programmes and close co-operation among all stakeholders on national and regional levels to effectively transfer experience and technical know-how to resuscitate and conserve soils, as well as how to improve crop production efficiency and security through the adoption by farmers of appropriate conservation tillage farming techniques.

The workshop warned that parts of Latin America and Africa could become dust bowls if farmers don't change their tillage practices. Every time a farmer tills his land, the soil structure is destroyed and the soil becomes more vulnerable to erosion. Conventional tillage with plough or hoe promotes erosion and biological degradation. In addition, ploughing with a motorised tractor or even draught animals and a mouldboard or disc plough forms plough layers, disrupting the exchange of water and air. If our arable soils are to survive, the way they are managed needs to be drastically changed.

It was a consensus in the workshop that current conventional tillage methods are a major cause of severe soil loss and desertification in many developing countries, and that the resultant soil erosion, accelerated by wind and water, is responsible for around 40 percent of land degradation world-wide. These Proceedings are presented in the hope that the conservation tillage practices and principles they expound will provide one more step towards an African agricultural renaissance that will lead this continent into a 21st century of sustainable agricultural production and food security.
 

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