What is Zero Tillage? Zero Tillage is the central element in what is now widely termed Conservation Agriculture. It brings a quantum leap in crop production technology, for it brings agriculture into harmony with nature. It puts into practice ideas first propounded by Edward Faulkner in his revolutionary and best-selling book, Ploughman's Folly, published in the USA in 1947. Faulkner had the audacity to challenge the paradigm that cultivating soil was beneficial. In a well-conceived argument, he showed that all standard wisdom used as a rationale for ploughing and working the soil was invalid.
Later, Louis Bromfield, the author of Malabat Farm and other classics, also crusaded against conventional methods of cultivation. However, all of these valiant efforts to put into practice a method of sod-seeding in a narrow strip opened by a chisel plough did not gain credibility. And it was not until the discovery of the first desiccant herbicide by a British chemical company in 1955 that the idea of eliminating soil cultivation completely began to gain expression.
Faulkner might have balked at the idea of using chemicals, yet it was the availability of desiccant herbicides that brought the most notable advances in developing Zero Tillage technology, in the USA (Phillips and Young, 1972). There was also progress in Zero Tillage in Europe, until the burning of straw in the fields was prohibited. This made planting very difficult with existing seed drills, and progress in Zero Tillage stalled. It is only now beginning to recover in this part of the world.
The main features of Zero Tillage and Conservation Agriculture and some of the advantages are briefly described in Box 1.
Zero Tillage (ZT) is suitable for small, medium and large farmers, using hand planting methods, animal traction, or mechanized planting/sowing. Plate 1 shows soybeans recently planted in a degraded Brachiaria decumbens pasture, a recent technological advance. Further technical details of Zero Tillage are summarized in Appendices 2 to 10.
PLATE 1
Soybeans Planted in Degraded Brachiaria Decumbens Pasture', Sinop-MT
The technological evolution and the expansion of Zero Tillage (ZT) in Brazil has been farmer-led. Its growth has been phenomenal, as shown in Figure 1. It will be noted from the graph that the tropical Cerrado region lagged behind the initial development in South Brazil by about 10 years. This lag subsequently allowed faster expansion with transfer of technology from the sub-tropics to the tropics, but the differences in climate required new agronomic solutions for the tropics. Farmers and technicians who adopted this technology have, so far, consistently resolved all of the challenges to its sustainability in the humid sub-tropics and humid wet-dry tropics of Brazil, with promising results in the humid tropics.
This case study examines the work and experience of a Brazilian NGO, the Zero Tillage Association for the Tropics (of Brazil), or ZTAT. This NGO came into being when about fifty farmers and technicians on a training course realized that they could help fill the existing gap in appropriate research information on the nascent Zero Tillage technology for the tropics. ZTAT has played a key role in helping to disseminate the technology in the tropical region of the country. From a modest beginning, it took only eight years for ZTAT to become a significant and representative force in the region.
Figure 1:Expansion of the Zero-Tillage Area in Brazil and in the Cerrado (wet/dry tropical savannah region).
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A long crusade was needed to break down the natural resistance to change and to promote ZT technology. Fruitful partnerships were forged with government and private sectors, and a network of local farmers' clubs was created with the sole objective of disseminating and improving Zero Tillage technology. In the event, Zero Tillage proved attractive to farmers because of its lower production costs, and also because it provides more planting days, a simpler operation to manage, greater drought tolerance, reduced investment/replacement costs for farm machinery, and generally higher yields. The farmers themselves have been extremely active in promoting the new technology.
The case study also incorporates an analysis of the new ZT principles, and of the impact, dissemination and adoption mechanisms of this new technology for sustainable intensification of natural resource management (SINRM). The analysis is based on the large-scale and continuing change from Conventional Tillage (CT) to ZT seen in Brazil. By 1999/2000, an estimated national total of 12 million ha were being farmed under ZT technology, about 30% of the area of annual summer crops. The tropical region represents one third of Brazil's ZT area.
