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Press Release 98/42

 

FAO: CONVENTIONAL TILLING SEVERELY ERODES THE SOIL; NEW CONCEPTS FOR SOIL CONSERVATION REQUIRED

 

  


 

Rome, 22 June -- Millions of hectares of agricultural land could be protected or saved from degradation and erosion if farmers applied environmentally friendly tillage, the UN Food and Agriculture Organization (FAO) said today. Current conventional tillage methods are a major cause of severe soil loss and desertification in many developing countries and soil erosion, accelerated by wind and water, is responsible for around 40 percent of land degradation world-wide, according to FAO.

"Tillage erosion damages soil in most developing countries where soil losses could exceed 150 tons per hectare annually," said FAO expert José Benites of the Soil Resources Management and Conservation Service. "Land degradation also occurs in developed countries due to exaggerated mechanised tillage resulting from the use of powerful heavy machines."

"Parts of Latin America and Africa could become dust bowls if farmers don't change their tillage practices", warns FAO. "Every time a farmer tills land to control weeds, the soil becomes more vulnerable to erosion and the soil structure is destroyed. Conventional tillage with tractors and ploughs provokes soil compaction and biological degradation. Even animal traction systems, to a lesser extent, can lead to erosion. The way soils are cultivated today needs to be drastically changed."

In general, soils in tropical countries do not need to be tilled, Benites said. "Interventions using machinery should be reduced to the minimum possible. The most desirable form of tillage is conservation tillage which leaves a protective blanket of leaves, stems and stalks from the previous crop on the surface. This cover shields the soil surface from heat, wind, and rain, keeps the soils cooler and reduces moisture losses by evaporation. Less tillage also means lower fuel and labour costs".

The reduction of tillage to the minimum possible has been applied by farmers for a long time. But according to FAO, "with the advent of tractors, the tendency was to increase tillage and farmers started to believe that the more you till the soil, the more yield you get. The truth is, that more tillage causes more erosion and soil degradation, especially in warmer areas where the topsoil layer is thin".

In many countries, including Brazil, Nicaragua, China, Malawi and Kazakstan, once fertile soils have been eroded by excessive soil cultivation. Compacted soil inhibits water infiltration and run off in the rainy season and creates gullies. Appropriate land preparation together with crop rotation can prevent such soil erosion. "A living and stable soil structure is essential to enhance water infiltration that prevents soil erosion," Benites said.

Today, the concept of conservation tillage is mainly applied in the Americas where more than 14 million hectares are cultivated this way; in contrast, only relatively small areas under conservation tillage are found in the rest of the world. Farmers could reduce the production costs of soybeans per acre with conservation tillage by $27 in Argentina, by $14 in the USA and by $11 in Brazil. "The reduction of costs is a very strong argument for conservation tillage," Benites said.

FAO is supporting reductions in the use of heavy tillage equipment, and is promoting greater use of conservation tillage and improved soil management through the formulation of a code of conduct on soil management. A workshop, to be held in Harare, Zimbabwe, 22-27 June, will promote the concept of conservation tillage, will prepare the outline of a regional project on conservation tillage, and will formulate the first draft of a code of conduct on soil management. The Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) from Germany, the South African Research Council, a Swedish funded FAO project and the Zimbabwe Farmers Union will participate in the meeting.

 

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