This study evaluated the early impacts of conservation agriculture (CA) compared to conventional agriculture (CV) on farmer income, soil fertility, and microbiota in Laos. Results after 3 seasons showed: 1) Similar production costs and yields but higher net income for CA due to byproduct sales. 2) Soil structure stability and carbon/nitrogen levels decreased under CV, with losses of 4Mg C/ha and 0.5Mg N/ha, but no losses under CA. 3) Bacterial/fungal biomass and diversity trended lower under CV compared to native pasture or CA. The study concluded CV had negative early agro-environmental impacts while CA maintained soil health and

1. Early effect of no-tillage on land profitability, soil fertility and microbiota A case study in a tropical ecosystem (altitude plains, Lao PDR) Pascal Lienhard, FlorentTivet, Andre Chabanne, Lucien Séguy, AnonhKhamhung, KhamkéoPanyasiri, Pierre-Alain Maron and Lionel Ranjard 5th World Congress on Conservation Agriculture - Brisbane, Australia, 26-29 September 2011

3. Material and methods: Experimental site & design, agri-environmental indicators

4. Results: Impact on farmers’ income, soil fertility evolution and microbiota

6. Material and methods: Experimental site & design, agri-environmental indicators

7. Results: Impact on farmers’ income, soil fertility evolution and microbiota

9. Main farming system: rice production in paddy fields and extensive livestock production in the hills

10. Limited possibilities to extend paddy areas

11. Limited agricultural production in the upland due to soil constraints (low pH, deficiencies in main nutrients, severe aluminium toxicity)

12. Only 5% of total surface is cultivated, 80% in paddy rice fields

16. Material and methods: Experimental site & design, agri-environmental indicators

17. Results: Impact on farmers’ income, soil fertility evolution and microbiota

20. All inputs, labor, and yields were collected to calculate 4y cumulated:

21. production costs (USD.ha-1) all inputs + operational costs

22. gross income (USD.ha-1) crops yield (kg.ha-1) x unit price (USD.kg-1)

23. net income (USD.ha-1 ) gross income – production costs

25. Soil sampling in June 2009

26. Bulk of 5 soil samples for each treatment

27. Soil analysis in France (CIRAD SAL)

28. pH water (1:5)

29. Org C (dry combustion)

30. Total N (dry combustion)

31. Available P (Olsen)

32. Effective CEC (cobalt hexamine)

34. Yoder method (1936) adapted by different authors (Haynes, 2000; Castro Filho, 2002; Madariet al, 2005)

35. 7 size classes of aggregates obtained after wet sieving of soil samples through 6 sieves (mesh of 8, 4, 2, 1, 0.5 and 0.25 mm)

36. 3 fieldreplicates per treatment

37. 4 aggregation parameters:

38. Macro (0.25-19mm) and micro (<0.25mm) aggregate content

39. Mean Weight Diameter (MWD)

40. Mean Geometric Diameter (MGD)

43. Analysis of microbes abundance and diversity

45. Material and methods: Experimental site & design, agri-environmental indicators

46. Results: Impact on farmers’ income, soil fertility evolution and microbiota

49. 2007: Ruzi grass seeds collected for sale

52. Early macroaggregate disruption process under CV

53. Higher soil sensitivity to erosion

55. Lower C and N content and stocks under CV

56. Mean loss of 4 Mg of TOC/ha and 0.5 Mg of TN/ha under CV after only 3 cropping seasons !

58. But…

62. Similar to Ranjardet al findings (2010): main driving factor explaining soil microbial distribution related to texture, pH and total org C

64. Material and methods: Experimental site & design, agri-environmental indicators

65. Results: Impact on farmers’ income, soil fertility evolution and microbiota

68. Main constraints are related to:

69. financial capital access

70. information