2. Agronomic Practices for Smallholder Cassava Farmers Reinhardt Howeler and Tin Maung Aye Accra, October, 2010

4. Cassava yields in Thailand as affected by area under new varieties, fertilizer use and cassava root price 1990-2010 18.78 2,777 221 68.9 2010 22.68 1,668 229 70.3 2009 21.26 2,071 204 71.8 2008 22.92 1,753 197 79.9 94.6 2007 21.09 1,338 189 82.1 95.0 2006 19.30 1,061 172 56.2 97.9 2003 17.07 1,287 175 66.4 91.1 2002 16.86 850 91.1 2000 15.49 1,030 86.9 1999 14.93 1,780 80.8 1998 14.16 1,390 39.0 1996 13.02 1,620 23.8 1995 14.03 3.5 1992 13.91 1.1 1990 Average cassava yield (t/ha) Cassava root price (baht/t) Quantity of chem. fertil. applied (kg/ha) Cassava area receiving chem. fertilizers (%) Cassava area planted to new varieties (%) Year of harvest

5. Trend in the percent of the total cassava area planted to new varieties and the percent yield increase in Thailand from 1990 to 2010 (2003 = 100%)

6. How can farmers increase their cassava yields in a sustainable way?

8. What is the best time to plant and to harvest cassava?

9. Cassava root yield (t/ha) Effect of month of planting and age at harvest on root yields of cassava cultivars Rayong 2 and Rayong 3 planted at Rayong Field Crops Research Center in 1983-1985. Source: Field Crops Research Institute, Annual Report 1986. 12 months 10 months 8 months 6 months Age at harvest Rayong 2 (1984/85) 0 20 40 60 30 50 10 0 20 40 May June July Aug Sept Oct Rayong 3 (1983/84 and 1984/85) Month of planting 30 10

10. Land preparation

13. Cutting stems into stakes

14. Manual planting Planting distance 0.8 x 0.8 to 1 x 1 m Mechanized planting

15. Rainy season planting Dry season planting Weeks after planting 15 10 5 0 Cassava root yield (t/ha) 100 80 60 40 20 0 Germination (%)             15 10 5 0 Cassava root yield (t/ha) V I H    Vertical Inclined Horizontal Germination (%) 100 80 60 40 20 0 1 2 3 4           

16. Response to N in Nanning, China ..to P and K in Xieng Khouang, Laos ..to K in Kampong Cham, Cambodia Adequate and well-balanced fertilization depends on the crop and the soil

17. Effect of annual applications of various levels of N, P and K on the root yield and starch content of two cassava varieties grown in Hung Loc Center in Vietnam in 2007/08 (18 th crop cycle)

18. After 31 years of continuous cropping in Khon Kaen, Thailand; without K in front, with well-balanced fertilizers in the back

19. In most soils in Asia, cassava needs Or, a fertilizer ratio of 10-5-15 - Potassium - Nitrogen - Phosphorus

20. Be aware! Cassava can cause serious soil erosion, even on gentle slopes….. … .if large amounts of run-off water accumulate in natural drainage ways

21. Soil loss by erosion can be a serious problem when the crop is planted on steep slopes

22. Fertilizer application improves canopy development and is therefore one of the most effective ways to reduce runoff and erosion

23. Months after planting Accumulative dry soil loss (t/ha) Effect of various soil/crop management practices on the accumulative dry soil loss by erosion at the Royal Project site in Pluak Daeng, Rayong, Thailand during a ten month growth cycle of cassava in 1990/91. 0 200 400 J J A S O N D J F M A M Rainfall (mm) 0 5 10 15 20 25 30 2 4 6 8 10 0 12 no fertilizers up-down ridging 1 plowing, 1 discing cassava harvester peanut intercrop closer spacing no tillage contour ridging

24. Contour hedgerows of vetiver grass (in back) are also very effective in reducing erosion

25. Trend in relative yield and relative soil loss by erosion when cassava was planted with contour hedgerows of vetiver grass, Leucaena leucocephala or Gliricidia sepium in comparison with the check without hedgerows during six consecutive years in Hung Loc Agric. Research Center in South Vietnam from 1997 to 2003. check without hedgerows Relative yield or soil loss (%) Year after planting hedgerows 0 20 40 60 80 100 120 140 160 180 200 1 2 3 4 5 6 7 Yield Soil loss Vetiver = Leucaena = Gliricidia =

26. Seven years after planting contour hedgerows of vetiver grass in Hoa Binh, these had caused the formation of natural terraces which markedly reduced erosion … .and after ten years in Khieu Thung, Phu Tho, Vietnam

27. Weed Control Cassava is a weak competitor, and its growth and yield are seriously reduced by weed competition Cassava fields need to be weeded at least 2-3 times during the crop cycle, usually at 1, 2 and 3 months after planting

29. The accidental introduction of the mealybug Phenacoccus manihoti into Thailand in 2008 has had a devastating effect on the whole cassava sector … and a new witches broom-like disease in Vietnam

31. While many experiments have shown ways to increase yields, farmers seldom adopt improved agronomic practices, because: - they may not know the best and most efficient production practices - some recommended practices are not effective under the farmer’s particular conditions, or do not fit well in their farming systems - the recommended practices are too costly or too labor-intensive - they do not provide short-term economic benefits

33. Farmer Participation and Decision Making Problem diagnosis with farmers Researchers show many technology options in FPR demonstration plots Feed back to research Adopt and disseminate Farmers adapt new practice and scale-up to production field Farmers retest and reselect Farmers select best options Farmers evaluate and select most suitable options/practices Farmers test options in FPR trials on their own fields Farmer Participatory Research (FPR) approach

34. Using RRAs, we l earn ed about farmers’ conditions, needs and concerns

35. We set out demonstration plots and let farmers evaluate the various options and select those that seem most promising

36. Farmers conduct FPR erosion control trials in their own fields

37. … .where they can clearly see that some simple practices can markedly reduce runoff and erosion

38. Farmers, researchers and extension workers evaluate the treatments in all the FPR trials conducted in the village Field day at time of harvest

39. After evaluating the trials in the field, farmers discuss the results together to select the best varieties and practices Field day at time of harvest

40. Location of FPR pilot sites in China, Thailand and Vietnam in the Nippon Foundation cassava project in 2003. 1 2 3 4 5 6       7 8 9 10 11      12  13  14  •    28  27 25  26  15  16  17  18  19  20  21  22  23  24 29  30 • •  31 32               5 1 2 3 4 6 7 10 11 12 13 14 15 16    9 8 17  18  19  20  21  22  23  24     28 27   26 25 29      32 31 30 33 34 • • •   1 2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33 • • • • •

42. Thong Nhat commune in North Vietnam in 1998 Serious erosion problems and low yields of cassava and tea The Impact!!

43. Thong Nhat commune in North Vietnam in 2000 A farmer proudly shows off his “new cassava” field

44. Figure 1. Average cassava yields of farmers participating in the Nippon Foundation cassava project or of nearby but non-participating farmers, before the project started and at the end of the project. Data are from PRRA census forms collected from 439 households in Thailand and 393 household in Vietnam. For comparison the national average cassava yields in 1999 (before) and 2003 (after) are also shown = Project participants = Non - participants = All country (1999-2003) Before project Before project After project 0 5 10 15 20 25 30 After project 0 5 10 15 20 25 30 Thailand Vietnam Cassava yield (t/ha)

45. Figure 1. Trend of cassava yields in Africa, Latin America and Asia from 1961 to 2007. Year 20 1960 18 16 14 12 10 8 6 4 2 0 1970 1980 1990 2000 2010 Cassava yield (t/ha) Asia Americas Africa 20 18 16 14 12 10 8 6 4 2 0

46. Helping farmers to conduct simple FPR trials on their own fields is the best way to achieve adoption of improved varieties and agronomic practices that will increase cassava yields and farmer’s income

47. Is this going to be the future of our children?

48. …… .or c an we help cassava farmers improve their livel i hood by producing enough food AND feedstock for starch and biofuel?