Preface

Zero Tillage is the main element among several that make up what FAO terms Conservation Agriculture (CA). Although CA uses some specific practices, and may also use external inputs, it is in essence an agricultural concept that conserves and enhances soil fertility, improves the availability of soil moisture, and increases the soil's biological resources. The adoption of CA leads to conservation of the environment and to a reversal of the soil degradation processes so common worldwide. At the same time, experience shows that it increases crop yields but with lower production costs, mainly due to reduced labour inputs, which frees time for other productive or income-generating activities. In effect, the system brings high agricultural productivity combined with the sustainable use of natural resources, and FAO is therefore promoting it vigorously.

The key practices in CA are:

• No soil inversion and reduction or total elimination of mechanical soil disturbance, except to inject seeds or plants into the soil by direct drilling techniques
• Maintenance at all times of a complete soil cover consisting of cover crops and/or crop residues
• Crop rotations judiciously selected to enhance the crop environment and to avoid build-up of pests and diseases

In this Case Study, the author uses the term "Zero Tillage", but it generally encompasses the other measures that constitute CA. It should be noted, however, that Zero Tillage needs to be continuous and permanent - not merely Zero Tillage for one crop in a rotation - for it to become true CA. Zero Tillage and "No-Tillage", or "No-Till", are synonymous terms used in different parts of the world.

The adoption of CA goes counter to the notion in force for thousands of years that soil must be cultivated before sowing or planting. It therefore requires a complete change in the mindset of those involved, whether farmers, extensionists, or scientists. Teaching the concept of CA, and examining methods and experiences of introducing it into farming practice, are essential for achieving the necessary changes in attitude and behaviour among present and future agricultural researchers, technicians and practitioners. The experience described in this Case Study is rich in insights into how the phenomenal growth of CA in Brazil, and especially in the tropical areas, has been promoted.

Given its potential for increased productivity, sustainable use of resources, environmental benefits beyond the farm, and improved socio-economic status for the rural poor, FAO is glad to see Zero Tillage/Conservation Agriculture included in the joint project between the University of Wageningen and FAO on Education for Decision-Making in the Global Arena of Agriculture.

J. Benites and Th. Friedrich
Conservation Agriculture Working Group, FAO