1. Introduction to Conservation Agriculture and Conservation Farming P.C. Wall CIMMYT ®

2. What is Conservation Agriculture? An array of technologies such as residue retention, zero- and reduced tillage, crop rotations, green manure cover crops, controlled traffic and raised beds. When used in combination these, over time, reduce, and often revert, the degradation of soil and water resources. Residue retention distinguishes conservation agriculture from conventional agriculture, and all conservation systems include at least a certain level of surface residue cover.

3. Some Characteristics of Conservation Agriculture Comprises two basic components  Surface crop residue retention  Minimal soil movement

4. Some Characteristics of Conservation Agriculture Plus other components essential to overcome problems that emerge once crop residues are retained:  Crop rotation  (Green manure cover crops)

5. Conservation Agriculture is a complex technology: it involves a complete change in the agricultural system.

6. Why the term “Conservation Agriculture”? To distinguish it from Conservation Tillage = 30% ground cover after seeding Take the emphasis off the word “tillage”

7. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralise nitrogen Eliminate compacted zones Incorporate fertilizers and ammendments Control diseases and pests Control water run-off Accumulate water

11. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralise nitrogen Eliminate compacted zones Incorporate fertilizers and ammendments Control diseases and pests Control water run-off Accumulate water

15. Conservation Agriculture with Planting Basins Both the basins and the mulch provide benefits – together they provide the optimum

16. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralise nitrogen Eliminate compacted zones Incorporate fertilizers and ammendments Control diseases and pests Control water run-off Accumulate water

17. Nitrogen mineralization implies organic matter breakdown It is a “quick fix”. It is a dwindling short- term gain that causes long-term harm. The release of nitrogen after tillage comes in a “flush” and considerable amounts may be lost. In conservation agriculture organic matter breakdown is reduced, and so a little more nitrogen must be added to the system, at least for the first few years.

19. Effect of Tillage on Soil Rhizobium Populations From Voss and Sidiras, 1985

20. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralise nitrogen Eliminate compacted zones Incorporate fertilizers and ammendments Control diseases and pests Control water run-off Accumulate water

24. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralise nitrogen Eliminate compacted zones Incorporate fertilizers and ammendments Control diseases and pests Control water run-off Accumulate water

25. Adapted from Sidiras and Pavan, 1985

29. Effect of Tillage on Earthworm Populations Source : Derpsch et al., 1991. Oxisol :- 0-30 cm. after 4 years Alfisol :- 0-10 cm. after 1.5 years 2

30. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralise nitrogen Eliminate compacted zones Incorporate fertilizers and ammendments Control diseases and pests Control water run-off Accumulate water

31. Monoculture leads to a build-up of pests and diseases. This is far more marked in zero tillage than in conventional tillage The key to controlling pests and diseases in zero tillage agriculture is crop rotation. One should avoid seeding a crop into it’s own residues before these are decomposed.

32. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralise nitrogen Eliminate compacted zones Incorporate fertilizers and ammendments Control diseases and pests Control water run-off Accumulate water

34. Effect of Tillage on Water Erosion

35. Why Soil Tillage? Weed Control Prepare a seed-bed Mineralize nitrogen Eliminate compacted zones Incorporate fertilizers and amendments Control diseases and pests Control water run-off Accumulate water

36. Effect of Tillage and Residue Cover on Water Infiltration Treatment% Residue Cover % Water Runoff Soil Loss t/ha Deep plough, disc09028.5 Rip, disc10706.7 Chisel plough, cultivate 30341.6 Zero tillage8061.0 Cedara Agric. Res. Stn, Kwazulu-Natal, RSA 63mm in 1 hour – 4% slope.

37. Aesthetics!

38. World wide adoption of Zero-tillage 2002 Millions of hectares Total = 67 million ha. Australia 9.0 Rest of the World 1.4 Canada 4.1 USA 21.1 Brazil 17.3 Paraguay 1.3 Argentina 11.7 Ghana: 100.000 small farmers use NT IGP 0.2 China 1.0? Based on Derpsch 2002

39. Farmers Perceptions of the Benefits of Conservation Agriculture

40. The principles of conservation agriculture appear to have extremely wide application The actual formulae and technologies for applying these principles are very site- specific.