Early effect of no-tillage on land profitability, <br />soil fertility and microbiota<br />A case study in a tropical ecos...
CONTENT<br /><ul><li>Context: Main farming systems and agricultural changes in the Plain of Jars
Material and methods: Experimental site & design, agri-environmental indicators
Results: Impact on farmers’ income, soil fertility evolution and microbiota
Conclusions: global agri-environmental evaluation of agricultural management</li></li></ul><li>CONTENT<br /><ul><li>Contex...
Material and methods: Experimental site & design, agri-environmental indicators
Results: Impact on farmers’ income, soil fertility evolution and microbiota
Conclusions: global agri-environmental evaluation of agricultural management</li></li></ul><li>Plain of Jars (900-1200m)<b...
 Main farming system: rice production in paddy fields and extensive livestock production in the hills
Limited possibilities to extend paddy areas
Limited agricultural production in the upland due to soil constraints (low pH, deficiencies in main nutrients, severe alum...
Only 5% of total surface is cultivated,     80% in paddy rice fields
Livestock system: low stocking rate, low investments</li></li></ul><li>Main changes in the uplands<br /><ul><li> Since 199...
Study objectives<br /><ul><li>Early effect </li></ul>(after 3 cropping seasons)<br /><ul><li>of various agricultural manag...
CONTENT<br /><ul><li>Context: Main farming systems and agricultural changes in the Plain of Jars
Material and methods: Experimental site & design, agri-environmental indicators
Results: Impact on farmers’ income, soil fertility evolution and microbiota
Conclusions: global agri-environmental evaluation of agricultural management</li></li></ul><li><ul><li> Ban Poaexperimenta...
Economical data collection<br /><ul><li>Data collection over 2007-2010 period
All inputs, labor, and yields were collected to calculate 4y cumulated:
production costs (USD.ha-1)              all inputs + operational costs
gross income (USD.ha-1)               crops yield (kg.ha-1) x unit price (USD.kg-1)
 net income (USD.ha-1 )               gross income – production costs
Calculations are made with constant average price in USD over the 4y-period</li></li></ul><li><ul><li> Soil chemical chara...
 Soil sampling in June 2009
 Bulk of 5 soil samples for each treatment
 Soil analysis in France (CIRAD SAL)
 pH water (1:5)
 Org C (dry combustion)
 Total N (dry combustion)
 Available P (Olsen)
 Effective CEC (cobalt hexamine)
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Early effect of no - tillage on land profitability, soil fertility and microbiota: A case study in a tropical ecosystem (altitude plains, Lao PDR)

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  • Conclusion We confirm that CA practices can both restore the soil fertility and improve farmers income main problem are the access to capital (cradit), information and the availability of an efficienct commodity chain to market products
  • Early effect of no - tillage on land profitability, soil fertility and microbiota: A case study in a tropical ecosystem (altitude plains, Lao PDR)

    1. 1. Early effect of no-tillage on land profitability, <br />soil fertility and microbiota<br />A case study in a tropical ecosystem (altitude plains, Lao PDR)<br />Pascal Lienhard, FlorentTivet, Andre Chabanne, Lucien Séguy, AnonhKhamhung, KhamkéoPanyasiri, Pierre-Alain Maron and Lionel Ranjard<br />5th World Congress on Conservation Agriculture - Brisbane, Australia, 26-29 September 2011<br />
    2. 2. CONTENT<br /><ul><li>Context: Main farming systems and agricultural changes in the Plain of Jars
    3. 3. Material and methods: Experimental site & design, agri-environmental indicators
    4. 4. Results: Impact on farmers’ income, soil fertility evolution and microbiota
    5. 5. Conclusions: global agri-environmental evaluation of agricultural management</li></li></ul><li>CONTENT<br /><ul><li>Context: Main farming systems and agricultural changes in the Plain of Jars
    6. 6. Material and methods: Experimental site & design, agri-environmental indicators
    7. 7. Results: Impact on farmers’ income, soil fertility evolution and microbiota
    8. 8. Conclusions: global agri-environmental evaluation of agricultural management</li></li></ul><li>Plain of Jars (900-1200m)<br /><ul><li>3 western districts (Pek, Phoukout and Paxay) of XiengKhouang province, north -eastern Lao PDR</li></li></ul><li>Plain of Jars (900-1200m)<br /><ul><li>About 80.000 ha of savannah grasslands with pine trees on hills summit
    9. 9. Main farming system: rice production in paddy fields and extensive livestock production in the hills
    10. 10. Limited possibilities to extend paddy areas
    11. 11. Limited agricultural production in the upland due to soil constraints (low pH, deficiencies in main nutrients, severe aluminium toxicity)
    12. 12. Only 5% of total surface is cultivated, 80% in paddy rice fields
    13. 13. Livestock system: low stocking rate, low investments</li></li></ul><li>Main changes in the uplands<br /><ul><li> Since 1990’s</li></ul>Reforestation (pine trees) policy and upland rice production attempts based on plowing with disks<br /><ul><li> Since 2000’s</li></ul>Attribution of large concessions to private companies for cash crops production (cassava, corn, jatropha); land preparation based on deep soil plowing<br /><ul><li> Since 2005</li></ul>Conception and promotion of CA-DMC systems as an ecologically-sound alternative to tillage-based agriculture<br />However, little information regarding agri-environmental impacts of these practices on soils for such agro-ecology<br />
    14. 14. Study objectives<br /><ul><li>Early effect </li></ul>(after 3 cropping seasons)<br /><ul><li>of various agricultural management</li></ul>(conservation vs conventional agriculture)<br /><ul><li> on profitability</li></ul>(farmers income)<br /><ul><li> soil fertility </li></ul>(chemical car. and soil aggregate stability)<br /><ul><li> and microbiota</li></ul>(abundance and diversity)<br /><ul><li>in a specific agro ecology </li></ul>(tropical climate, mountainous areas)<br />
    15. 15. CONTENT<br /><ul><li>Context: Main farming systems and agricultural changes in the Plain of Jars
    16. 16. Material and methods: Experimental site & design, agri-environmental indicators
    17. 17. Results: Impact on farmers’ income, soil fertility evolution and microbiota
    18. 18. Conclusions: global agri-environmental evaluation of agricultural management</li></li></ul><li><ul><li> Ban Poaexperimental site (created in 2007)</li></li></ul><li><ul><li>Treatments</li></ul>PAS<br />CV<br />DMCs<br />
    19. 19. Economical data collection<br /><ul><li>Data collection over 2007-2010 period
    20. 20. All inputs, labor, and yields were collected to calculate 4y cumulated:
    21. 21. production costs (USD.ha-1) all inputs + operational costs
    22. 22. gross income (USD.ha-1) crops yield (kg.ha-1) x unit price (USD.kg-1)
    23. 23. net income (USD.ha-1 ) gross income – production costs
    24. 24. Calculations are made with constant average price in USD over the 4y-period</li></li></ul><li><ul><li> Soil chemical characteristics
    25. 25. Soil sampling in June 2009
    26. 26. Bulk of 5 soil samples for each treatment
    27. 27. Soil analysis in France (CIRAD SAL)
    28. 28. pH water (1:5)
    29. 29. Org C (dry combustion)
    30. 30. Total N (dry combustion)
    31. 31. Available P (Olsen)
    32. 32. Effective CEC (cobalt hexamine)
    33. 33. Exchangeable base (Ca, Mg, K, Na) (cobalt.)</li></li></ul><li><ul><li> Soil Aggregate Stability
    34. 34. Yoder method (1936) adapted by different authors (Haynes, 2000; Castro Filho, 2002; Madariet al, 2005)
    35. 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. 36. 3 fieldreplicates per treatment
    37. 37. 4 aggregation parameters:
    38. 38. Macro (0.25-19mm) and micro (<0.25mm) aggregate content
    39. 39. Mean Weight Diameter (MWD)
    40. 40. Mean Geometric Diameter (MGD)
    41. 41. Aggregate Stability Index (AS)</li></li></ul><li><ul><li> The mean-weight diameter (MWD) of aggregates is an estimate of the size of the heaviest aggregate size classes:</li></ul>where wi is the proportional weight of each aggregate class in relation to the whole and xi is the mean diameter of the considered class (mm). <br /><ul><li> The Mean geometric diameter (MGD) of aggregates is an estimate of the size of the most frequent aggregate size classes:</li></ul>where wi is the weight (g) of the aggregates of each size class and ln xi the natural logarithm of the mean diameter of the size class.<br /><ul><li> The Aggregate stability index (AS) of soils is a measure of the total aggregation of the soil:</li></ul>where wp25 is the weight (g) of aggregates <0.25 mm and sand is the weight (g) of particles between 53 and 2000 µm. It is expressed in percent.<br />
    42. 42. <ul><li> Soil microbiota
    43. 43. Analysis of microbes abundance and diversity
    44. 44. Molecular tools</li></li></ul><li>CONTENT<br /><ul><li>Context: Main farming systems and agricultural changes in the Plain of Jars
    45. 45. Material and methods: Experimental site & design, agri-environmental indicators
    46. 46. Results: Impact on farmers’ income, soil fertility evolution and microbiota
    47. 47. Conclusions: global agri-environmental evaluation of agricultural management</li></li></ul><li><ul><li> Economical performances of CA vs CV systems</li></ul>2007-2010 cumulated data for the following crop sequences:<br />rice 2008, corn 2009, soybean 2010 (2007: cover crops for DMCs and nat past for CV)<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li>Similar cumulated prod. costs over 2007-2010 but…
    48. 48. Different trends with expected CV prod. costs > DMCs prod costs in 2011</li></li></ul><li><ul><li> Economical performances of CA vs CV systems</li></ul>2007-2010 cumulated data for the following crop sequences:<br />rice 2008, corn 2009, soybean 2010 (2007: cover crops for DMCs and nat past for CV)<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li>Similar grain yields and gross income over 2007-2010, but…</li></ul> …By-products of DMCs systems are not taken into the economical calculation<br /><ul><li> 2007: Finger millet and pigeon pea used for pig fattening
    49. 49. 2007: Ruzi grass seeds collected for sale
    50. 50. 2009 & 2010 ruzi grass forage cut and exported for cattle fattening activities </li></li></ul><li><ul><li> Economical performances of CA vs CV systems</li></ul>2007-2010 cumulated data for the following crop sequences:<br />rice 2008, corn 2009, soybean 2010 (2007: cover crops for DMCs and nat past for CV)<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li>Similar cumulated net income (except for ruzi-grass based DMC3)
    51. 51. Return on investment after 3 cropping seasons</li></li></ul><li><ul><li> Land use impact on top soil (0-10cm) aggregate stability</li></ul>MWD = Mean Weight Diameter; MGD = Mean Geometric Diameter; AS = Aggregate Stability Index<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li> Soil structure stability decrease under CV compared to PAS and DMC
    52. 52. Early macroaggregate disruption process under CV
    53. 53. Higher soil sensitivity to erosion
    54. 54. Higher exposition of SOC to microbes and mineralization (since C is physically protected into microaggregates that are formed into macroaggregates, Six et al, 2004)</li></li></ul><li><ul><li> Land use impact on top soil (0-10cm) chemical characteristics</li></ul>1 C stock (Mg/ha) = Org C (%) x Da (g.cm-3) x layer depth (cm) x 10; <br />2 N stock (Mg/ha) = Total N (‰) x Da (g.cm-3) x layer depth (cm)<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li>Lower Bulk density under CV compared to PAS and DMCs
    55. 55. Lower C and N content and stocks under CV
    56. 56. Mean loss of 4 Mg of TOC/ha and 0.5 Mg of TN/ha under CV after only 3 cropping seasons !
    57. 57. No losses under DMCs</li></li></ul><li><ul><li> Land use impact on top soil chemical characteristics</li></ul>1 BS = Base saturation= (Ca+Mg+K+Na)×100 / CEC<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li> General improvement of soil chemical fertility under fertilized agro-systems (CV and DMCs) compared to native pastureland (PAS) due to lime + thermo phosphate applications</li></li></ul><li><ul><li> Land use impact on top soil chemical characteristics</li></ul>1 BS = Base saturation= (Ca+Mg+K+Na)×100 / CEC<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li> General improvement of soil chemical fertility under fertilized agro-systems (CV and DMCs) compared to native pastureland (PAS) due to lime + thermo phosphate applications
    58. 58. But…
    59. 59. Better fertilizer use under DMCs (higher lixiviation rates under CV)</li></li></ul><li><ul><li> Land use impact on top soil chemical characteristics</li></ul>1 BS = Base saturation= (Ca+Mg+K+Na)×100 / CEC<br />Letters between brackets indicate significant differences according Kruskal-Wallis test (p<0,05), Bonferroni correction<br /><ul><li> Decrease of pH under CV despite lime and thermo phosphate applications
    60. 60. Might be related to the release of protons (H+) during the oxidation of carbon (C) and nitrogen (N) compounds in soils (tillage)</li></li></ul><li><ul><li> Land use impact on top soil (0-10cm) micro biota abundance</li></ul>Trend of decrease of bacterial and fungal biomasses under CV compared to PAS and DMCs<br />
    61. 61. <ul><li> Land use impact on top soil (0-10cm) micro biota diversity</li></ul>PCA of B-ARISA fingerprints<br />Total soils (n=114), <br />from clay to sandy loam<br />Clay soils (n=66)<br /><ul><li> Effect of texture > effect of land use
    62. 62. Similar to Ranjardet al findings (2010): main driving factor explaining soil microbial distribution related to texture, pH and total org C
    63. 63. For given textural classes: trends of bacterial communities changes observed (DMCs ≠ PAS ≠ CV)</li></li></ul><li>CONTENT<br /><ul><li>Context: Main farming systems and agricultural changes in the Plain of Jars
    64. 64. Material and methods: Experimental site & design, agri-environmental indicators
    65. 65. Results: Impact on farmers’ income, soil fertility evolution and microbiota
    66. 66. Conclusions: global agri-environmental evaluation of the impact of native land conversion to agriculture</li></li></ul><li>PAS<br />DMCs<br />CV<br />Initial situation Extensive grazing on native grass<br />Early impact of land use conversion on…<br />* Under favorable conditions <br />AGRI-ENVIRON. SERVICES<br />++*<br />Farmers income<br />++*<br />SOIL QUALITY<br />+<br />--<br />Soil structure stability<br />-<br />+<br />Soil bulk density<br />Soil organic status<br />+<br />--<br />Soil nutrients availab.<br />++*<br />+*<br />Soil microbiota abundance<br />+<br />-<br />
    67. 67. Conclusions<br /><ul><li>Despite higher global agri-environmental services provided by CA-DMCs, tillage-based systems are still prevailing
    68. 68. Main constraints are related to:
    69. 69. financial capital access
    70. 70. information
    71. 71. and commodity chain</li></li></ul><li>Conclusions (2)<br /><ul><li> These first observations confirmed the early impact of ploughing on top soil degradation process and the interactions between Soil Organic Matter, soil biota and soil structure as described by Six et al (2002)
    72. 72. Macro aggregates disruption, enhanced soil aeration and mixing of residues into the soil induced changes in microbial biota and C and N losses</li></li></ul><li>Conclusions (3)<br /><ul><li> These results observed after only 3 years of cultivation also confirmed how fast soil degradation can occur in the tropics (even in altitude-cooler areas)</li></li></ul><li>Thank you for your attention !<br />

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